Wireless timing adjustment for multi-time domain periodic traffic

Abstract

A communication terminal for supporting a periodic data flow by forwarding messages received from a communication network to an external node that is not synchronized with the communication network, the communication terminal configured to: obtain one or more timing adjustment indications from an access node of the communication network; and adjust a transmission and / or reception timing of the periodic data flow in accordance with the one or more timing adjustment indications, wherein the one or more timing adjustment indications are based on clock mismatch information between the communication terminal and the external node and a holdover time.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to timing adjustment in wireless networks. BACKGROUND

[0002] To support Industrial Internet of Things (IIOT), 5G systems need to support multiple clock domains simultaneously, including a global time domain, different working clock domains, and time sensitive networking (TSN) clock domains.

[0003] At the same time, 5G systems shall maintain their own clock domain, which shall remain independent to adapt to different external clock domains in a neutral way. Different clock domains are usually driven by their individual grand master clocks, which are not synchronized to each other.

[0004] According to the specification of 3GPP TS 23.501, 5G networks have an independent 5G time domain, which is synchronized to its own 5G grand master (5G GM) clock, and implements E2E (End to end) synchronization between core network user plane functions (UPF), base stations such as gNodeB (gNB), and user equipment (UE), as well as device-side TSN translators (DS-TT) connected to the UE and network TSN translators (NW-TT) connected to the UPF. The NW-TT and DS-TT are also synchronized to the external TSN clock domain to support TSN time-sensitive systems or bridging functions. According to the specification of 3GPP TR 22.832, gNB needs to serve multiple clock domains.

[0005] Therefore, the challenge is that different clock domains all have their independent grand master (GM) clocks, and these clocks are expected to be unsynchronized.

[0006] Data traffic patterns from different working clock domains are driven by their respective GM clocks, and they are unsynchronized. 5G RAN transmission is driven by the 5G GM.

[0007] 3GPP TR 38.825 (FS_NR_IIOT) suggests that semi-persistent scheduling (SPS) for downlink (DL) and configured grant (CG) for uplink (UL) in the radio access network (RAN) are suitable to support periodic deterministic traffic patterns commonly found in industrial automation and control applications.

[0008] Understanding the TSN traffic pattern is beneficial for the gNB to be able to schedule more efficiently with CG / SPS or dynamic grant. In dynamic grant, the UL grant configuration and activation or deactivation of resources are signaled over the control channel. In CG, the UL grant configuration is provided by RRC signaling and activation or deactivation is provided by RRC signaling (Type 1) or through control channel or physical layer signaling (Type 2). Using CG / SPS has advantages over dynamic scheduling as it supports reduced PDCCH overhead and improved reliability by avoiding control channel blocking. In some references, CG is also referred to as configured scheduling (CS).

[0009] Therefore, timing mismatch issues arise in the RAN. The 5G clock domain, different working clock domains, and the GM clock of the TSN clock domain are not synchronized, which leads to timing mismatch between the scheduling of SPS / CG within the 5G system and the different traffic patterns of the application of the external clock domain.

[0010] For example, there can be two undesirable cases. Figures 1(a) and 1(b) show one case. When the transmission interval of the traffic is larger than the 5G local SPS / CG period, as shown in Figure 1(a), the delay jitter is large and sometimes the delay exceeds the limit value, as shown in Figure 1(b). Figures 2(a) and 2(b) show the second case. When the transmission interval of the traffic is smaller than the 5G local SPS / CG period, as shown in Figure 2(a), the delay keeps increasing and buffer overflow can occur, as shown in Figure 2(b). The simulation parameters used are shown in Figure 3

[0011] It is desirable to develop a wireless timing adjustment method that can overcome these issues. SUMMARY

[0012] ​According to a first aspect, there is provided a communication terminal for supporting a periodic data flow by forwarding messages received from a communication network to an external node that is not synchronized with the communication network, the communication terminal configured to: obtain one or more timing adjustment indications from an access node of the communication network; and adjust a transmission and / or reception timing of the periodic data flow in accordance with the one or more timing adjustment indications; wherein the one or more timing adjustment indications are based on clock mismatch information between the communication terminal and the external node and a holdover time. This can allow adjusting the timing of the periodic data flow transmitted to or from the communication terminal to mitigate the mismatch between the clocks of different domains.

[0013] The communication terminal can be further configured to: estimate the clock mismatch information between the communication terminal and the external node; and provide the estimated clock mismatch information and the holdover time to the access node of the communication network. This can allow providing the clock mismatch information and the holdover time to other components of the communication network.

[0014] The communication terminal can be configured to obtain the estimated clock mismatch information from the access node and adjust an egress transmission timing of the periodic data flow to mitigate the mismatch between the clock of the communication network and the clock of the external node. This can allow adjusting the transmission timing of the data flow from the communication terminal to mitigate the mismatch between the clocks of different domains.

[0015] The estimated clock mismatch information can be based on one or more of: (i) a number of periods in which the network transmits and / or receives messages of the periodic data flow in accordance with a frequency of an internal clock of the communication network; and (ii) a ratio of a frequency of the clock of the external node to a frequency of the internal clock of the communication network. These parameters can allow estimating the clock mismatch information.

[0016] The communication terminal can be configured to quantify the holdover time and report the holdover time to the access node. This can reduce the uplink overhead.

[0017] The communication terminal can be a user equipment and the access node can be a nodeB. This can allow using the communication terminal in a standard communication network.

[0018] The periodic data flow can be a semi-statically scheduled or configured grant data flow. The communication terminal can be configured to receive the timing adjustment indication in a downlink control message, a physical downlink control channel message or a radio resource control message.

[0019] According to a second aspect, there is provided a network node for operating in a communication network to support a periodic data flow by forwarding messages received by the network node to an external node that is not synchronised with the communication network, the network node being configured to estimate a clock mismatch between an internal clock of the communication network and a clock of the external node, and to send a message to an access node of the communication network, the message indicating the estimated clock mismatch. This can allow timing of a periodic data flow to be adjusted to mitigate a mismatch between clocks of different domains.

[0020] The estimated clock mismatch can be determined in accordance with one or more of: (i) a number of periods of messages of the periodic data flow received by the network in accordance with a frequency of the internal clock of the communication network; and (ii) a ratio of a frequency of the clock of the external node to a frequency of the internal clock of the communication network. These parameters can allow the clock mismatch to be estimated.

[0021] The network node can be configured to obtain clock mismatch information between a communication terminal and another external node from the access node, and to adjust an egress transmission timing of the periodic data flow to mitigate the clock mismatch between the internal clock of the communication network and the clock of the external node. This can allow transmission timing of a data flow from a network node to be adjusted to mitigate a mismatch between clocks of different domains.

[0022] The network node can be part of a core network, and the access node of the communication network can be a nodeB. This can allow the network node to be implemented in a standard communication network.

[0023] According to a third aspect, there is provided an access node for operating in a communication network to support a periodic data flow by forwarding messages received by the access node from another node of the network to a communication terminal, the access node being configured to receive clock mismatch information; and to perform at least one of: (a) sending a timing adjustment command to the communication terminal; (b) adjusting timing of the periodic data flow to the communication terminal in accordance with the clock mismatch information; and (c) sending the clock mismatch information to the communication terminal. This can allow timing of a periodic data flow to be adjusted to mitigate a mismatch between clocks of different domains.

[0024] The access node can be configured to send clock mismatch information to a communication terminal in a downlink control message, a radio resource control message or a medium access control element. This can conveniently provide clock mismatch information to a communication terminal.

[0025] The access node can be configured to adjust timing of transmission of a subsequent data packet of a periodic data flow, and to indicate the timing adjustment to a communication terminal. This can be done using, for example, a downlink control indicator. This can allow timing to be adjusted passively.

[0026] The access node can be configured to determine a number of future periods in which the timing of the transmission of the packets of the periodic data flow should be adjusted, and to indicate the number of periods to the communication terminal. This can be done using, for example, a radio resource control message. This can allow the timing to be actively adjusted in advance.

[0027] The other node can be part of a core network, the access node can be a NodeB, and the communication terminal can be a user equipment. This can allow the access node to be implemented in a standard communication network.

[0028] According to a fourth aspect, there is provided an access node configured to operate in a communication network to support a periodic data flow by forwarding messages received by the access node from a communication terminal of the communication network to another node of the communication network, the access node being configured to receive clock mismatch information and a holdover time from the communication terminal, and to send the clock mismatch information to the other node. This can allow the timing of a periodic data flow to be adjusted to mitigate a mismatch between clocks of different domains.

[0029] The access node can be configured to send the clock mismatch information as assistance information to the other node of the communication network. This can conveniently provide the clock mismatch information to the other node.

[0030] The access node can be a NodeB, the other node can be part of a core network, and the communication terminal can be a user equipment. This can allow the access node to be implemented in a standard communication network. BRIEF DESCRIPTION OF DRAWINGS

[0031] The application will now be described by way of example with reference to the accompanying drawings.

[0032] In the drawings:

[0033] Figure 1 (a) shows a graph of time versus frequency when the transmission interval of the data traffic is greater than the 5G local SPS / CG period.

[0034] Figure 1 (b) shows a graph of delay versus time when the transmission interval of the data traffic is greater than the 5G local SPS / CG period.

[0035] Figure 2 (a) shows a graph of time versus frequency when the transmission interval of the data traffic is less than the 5G local SPS / CG period.

[0036] Figure 2 (b) shows a graph of delay versus time when the transmission interval of the data traffic is less than the 5G local SPS / CG period.

[0037] Figure 3The simulation parameters used in Figures 1(a) and 1(b) and Figures 2(a) and 2(b) are shown.

[0038] Figure 4 Downlink SPS timing adjustment based on network-side measured clock mismatch in a communication network is schematically shown.

[0039] Figure 5 Uplink CG timing adjustment in a communication network is schematically shown.

[0040] Figure 6 Examples of passive SPS / CG timing adjustment with PDCCH are schematically shown.

[0041] Figure 7 Examples of active SPS / CG timing adjustment with RRC signaling are schematically shown.

[0042] Figures 8(a) and 8(b) show the effectiveness of timing adjustment for mitigating clock mismatch issues.

[0043] Figure 9 The simulation parameters used in Figures 8(a) and 8(b) are shown. DETAILED DESCRIPTION

[0044] Described herein is a communication network, which can be a network compatible with 5G network signaling. Each node and communication terminal of the network, as well as any node outside the network in communication with the nodes and / or communication terminals of the network, can comprise a wireless transceiver, a processor and a memory, with two parts for storing code and messages, respectively, and a clock. The communication terminal can further comprise a user interface for presenting information or for sensing environmental data. The user interface can comprise mechanisms for communicating or interacting with the environment or user of the device, such as a display, a touchscreen or one or more transducers. The communication terminal can be connected to a plurality of access nodes (e.g. base stations, such as gNBs). Such base stations can also communicate wirelessly with each other. The communication network can comprise at least one communication terminal, at least one access node and at least one network node in a core network of the communication network. It is assumed that these components of the communication network are already synchronized.

[0045] Figure 4The diagram schematically illustrates downlink (DL) SPS timing adjustment based on clock mismatch measured at the network side within a communication network. This network comprises multiple nodes. The internal communication network components of the 5G system, generally shown at 401, are the gNB 402, the core network (illustrated herein as UPF 403), and the UE device 404. These components are synchronized end-to-end according to the internal 5G system GM clock in the 5G clock domain. Entities 405 and 406 are external nodes (i.e., nodes outside the network) or end stations. These external nodes are not synchronized with the communication network. While referenced to a 5G system, the principles described in this disclosure are applicable to any network with an architecture compatible with 5G systems, particularly regarding timing adjustments.

[0046] like Figure 4 As shown in 407, the 5G system establishes a deterministic data stream with transmission intervals and delays based on the requirements of an external network or terminal station 405. For example, 405 could be a TSN network, or a controller, sensor, or actuator in industrial automation.

[0047] As shown in 408, gNB 402 is used to determine timing adjustment parameters, such as high / low thresholds (described below), based on information about the data stream (e.g., the number of periods of data bursts).

[0048] As shown in 409, the core network (in this example, the UPF 403 with a converter, specifically the network-side TSN translator (NW-TT)) measures the mismatch between the clock of the 5G system 401 and the external clock of the external node 405.

[0049] In some implementations, the clock mismatch information (CMI) can be described in one of two forms. Other forms may also be used.

[0050] In the first exemplary form, the mismatch can be given by the transmission interval or the number of cycles based on the frequency of the clock of the 5G system 401. For example, assuming that the external operating clock is 100 ppm (parts per million) slower than the 5G system clock, the nominal transmission interval of 1 ms is measured as 1.0001 ms by the 5G system.

[0051] In a second example form, the mismatch can be given by a rate ratio, which is the ratio of the frequency of the external clock domain (i.e. the domain frequency of the clock of the external node 405) to the frequency of the 5G system clock. In the example above, the rate ratio is 0.9999. In addition to measuring the CMI directly with the arrival time of data bursts or packets, the CMI, in particular the rate ratio, can also be obtained by the UPF 403 and / or the UE 404 using existing time synchronization mechanisms like IEEE 802.1 AS or IEEE 1588 (g) PTP mechanisms.

[0052] As shown at 410, the measured CMI is provided from the core network 403 to the gNB 402. This can be provided by another core network component, e.g. a session management function (SMF) component. For example, the rate ratio can be added to the time sensitive communication assistant information (TSCAI) sent between the UPF 403 and the gNB 402.

[0053] The measured CMI can also be further provided from the gNB to the UE, as shown at 411. This can be done using three approaches. In one approach, it can be provided in the RRC signaling configuring the SPS. For example, it can be added to the SPS-Config message. In a second implementation, it can be provided in a new type of RRC signaling including the CMI of the data flow. In a third implementation, it can be provided in a new type of media access control (MAC) control element (CE).

[0054] Both approaches can be applied to provide the CMI to the UE device at the SPS setup phase and to provide updates of the CMI to the UE continuously during the SPS run.

[0055] As shown at 412, the gNB 402 also measures the clock mismatch and additionally measures the jitter of the data flow from the UPF and can use a hold and forward mechanism to eliminate the jitter in the DL transmission of the radio access network (RAN).

[0056] The gNB 402 uses a timing adjustment method (described below) to adjust the timing of its downlink SPS transmissions, knowing the holdover time (time elapsed between the arrival of a data packet at the gNB or UE and the sending of the data packet by the gNB or UE) and the CMI. The gNB 402 commands the timing adjustment to the UE 404 in the form of a DL control information (DCI) (described below with reference to Figure 6 Figure 7

[0057] As shown at 413, the UE 404 uses the clock mismatch information obtained from the gNB 402 with the rate ratio and / or number of transmission intervals / periods to adjust the egress timing of data traffic to the external network or end station 406 with the holdover and relay mechanisms described herein.

[0058] Figure 5 Uplink (UL) CG timing adjustment based on CMI such as transmission interval or rate ratio measured at the UE device side of the network is shown schematically.

[0059] The internal network components of the 5G system, shown generally at 501, are a gNB 502, a core network (shown here as a UPF 503), and a UE device 504. These components are synchronized end-to-end according to the internal 5G system GM clock of the 5G clock domain. Entities 505, 506 are external nodes (i.e., nodes external to the network) or end stations. These external nodes are not synchronized to the communication network.

[0060] As shown at 507 in Figure 5 The 5G system establishes deterministic data flows with transmission intervals and delays according to the requirements of the external network or end station 506.

[0061] The 5G system 501 establishes deterministic data flows with transmission intervals and delays in the UL according to the requirements of the external network (e.g., a TSN network) or end station (e.g., a controller, sensor, or actuator in industrial automation).

[0062] As shown at 508, the gNB 502 determines timing adjustment parameters, such as high / low thresholds (described in the timing adjustment mechanisms below), based on information of the data flow (e.g., number of periods of data bursts).

[0063] ​​As shown in 509, the UE 504 (preferably with a translator, in particular a device-side TSN translator (DS-TT)) measures the mismatch between the 5G system clock and the external clock. Similar to the reference Figure 4 Similar to the description, the CMI can have one of two forms. In one form, the CMI is the number of transmission intervals / periods based on the frequency of the 5G system clock. In another form, the CMI is a rate ratio, i.e., the ratio of the frequency of the external clock domain to the frequency of the 5G system clock.

[0064] In addition to directly measuring the CMI with the arrival time of the data burst, the CMI (in particular the rate ratio) can also be obtained by the UPF and / or UE device using existing time synchronization mechanisms such as IEEE 802.1AS or IEEE 1588 (g) PTP mechanisms.

[0065] As shown in 510, the measured CMI is provided from the UE 504 to the gNB 502, e.g., with a MAC control element (CE).

[0066] As shown in 511, the measured CMI can be further provided from the gNB 502 to the core network (UPF 503). This can be provided by another core network component, e.g., a session management function (SMF) component. For example, it can be provided in time sensitive communication assistant information (TSCAI).

[0067] As shown in 512, the holdover time of the data burst at the UE device 504 (described below for the timing adjustment mechanism) is provided by the UE to the gNB 502 (e.g., with a MAC CE). The holdover time can be attached to the data burst (e.g., PDCP SDU). Alternatively, the holdover time can be included in a MAC CE (similar to a buffer status report (BSR)). Alternatively, a new dedicated MAC CE can be defined to report the holdover time.

[0068] The holdover time can be quantized to reduce the UL overhead, e.g.:

[0069]

[0070] where N is the number of bits. For example, 4 bits can represent the holdover time with a resolution of 1 / 16 number of periods.

[0071] As shown in 513, the gNB uses a timing adjustment method (described below) to adjust the timing of its UL CG transmissions, given the holdover time and CMI (both provided by the UE device).

[0072] In one example, the timing adjustment is commanded by the gNB to the UE in the form of DL control information (DCI) in a physical DL control channel (PDCCH) or radio resource control (RRC) signaling in the DL, as will be described in more detail below.

[0073] As shown in 514, the UE uses the CMI (i.e., the number of transmission intervals / periods or rate ratio) obtained from the gNB 502 to adjust the egress timing of data traffic to the external network or end station 506, with the holdover and forwarding mechanism described below.

[0074] The basic mechanism of timing adjustment (as described above) will now be described.

[0075] The mechanism is used by the gNB network node to determine at least one timing adjustment indication. The parameters used in describing the mechanism are summarized as follows:

[0076] ■n is the index of the CG / SPS transmission.

[0077] ■T Tx (n) is the scheduled transmission time before timing adjustment according to the CG / SPS schedule of data burst n.

[0078] ■T′ Tx (n) is the scheduled transmission time after timing adjustment.

[0079] ■T Arrival (n) is the time instant when data burst n arrives at the UE or gNB.

[0080] ■τ TxHold (n) = T Tx (n) - T Arrival (n) is the holdover time of data burst n, which is the time elapsed between the arrival of a data packet at the gNB or UE and the sending of the data packet by the gNB or UE. It should be in the range of [T thrLow ,T thrHigh ].

[0081] ■τ adj (n) is the timing adjustment factor determined by the gNB taking into account the signaling time, slot / frame boundary, and satisfying the following condition: T Tx (n) - τ adj (n) > TArrival (n)

[0082] Two exemplary methods of arranging timing adjustment will now be described.

[0083] In one method, a reactive approach can be used. In this approach, based on the current holding time, the scheduler can decide whether to perform timing adjustment immediately.

[0084] Based on the current holding time, the next transmission time is adjusted according to:

[0085] τ TxHold (n) = T Tx (n) - T Arrival (n)

[0086] If T Tx (n) - T Arrival (n) > T thrHigh

[0087] T' Tx (n) = T Tx (n) - τ adj (n)

[0088] Else if T Tx (n) - T Arrival (n) < T thrLow

[0089] T' Tx (n) = T Tx (n) + τ adj (n)

[0090] End

[0091] A DCI format 0_0, 0_1, 1_0, 1_1 or a new type of DCI format scrambled with CS-RNTI can be used to override the current CG / SPS, thus making a proactive adjustment. The new type of DCI format should at least include time domain resource allocation information.

[0092] The DCI format 0_0, 0_1, 1_0, 1_1 includes a “time domain resource allocation” field, which carries the row index of each item of pusch_allocationList or pdsch_allocationList in RRC.

[0093] The scheme of using a reactive timing adjustment is described as follows, and shown in Figure 6 Specifically, Figure 6Examples of passive SPS / CG timing adjustment with PDCCH are shown. The flow of downlink SPS is shown at 600 between UE 601 and gNB 602. The flow of uplink CG is shown at 650 between UE 651 and gNB 652.

[0094] The timing of SPS / CG can be passively adjusted using PDCCH, e.g., using DCI in PDCCH scrambled by CS-RNTI, for advancing or delaying the timing of next SPS / CG transmission. Some example choices to achieve this goal are:

[0095] Choice a: Use existing DCI formats (e.g., 0_0 & 0_1 (UL CS) and 1_0 & 1_1 (DL SPS)) with adjusted “Time domain resource allocation” field. Other existing parameters in DCI format (e.g., frequency domain resource allocation, MCS) can also be adjusted.

[0096] Choice b: Use new DCI format that includes at least “Time domain resource allocation” field or dedicated timing adjustment field to adjust the timing of SPS / CG transmission.

[0097] The timing adjustment (advance or delay τ adj ) takes effect before the current SPS / CG can continue with the same periodicity T, as shown in 610 and 660 in Figure 6

[0098] The timing adjustment DCI can be scrambled to the CS-RNTI that identifies the SPS or CG.

[0099] The “Time domain resource allocation” field carries the row index of each item in pusch_allocationList or pdsch_allocationList in RRC:

[0100] a. K0 (for DL) and k2 (for UL) values specify the slot offset relative to the current PDCCH.

[0101] b. startSymbolAndLength specifies the starting symbol (SLIV) within the slot and length.

[0102] In another approach, an active timing adjustment method can be used.

[0103] In the active method, Δn is the number of CG / SPS periods in the future that timing adjustment should be made.

[0104] The scheduler predicts the future n based on the current holding time, measured transmission interval or rate ratio, and SPS / CG periodicity:

[0105] ​

[0106] where R is the rate ratio.

[0107] The proactive timing adjustment can be done using existing RRC signaling for configuring CG / SPS (e.g., SPS-Config for DL SPS and ConfiguredGrantConfig for UL CG) or a new type of RRC signaling.

[0108] The scheme of using proactive timing adjustment is described as follows, as shown in Figure 7 Specifically, Figure 7 An example of proactive SPS / CG timing adjustment with RRC signaling is shown. The flow of downlink SPS is shown at 700 between UE 701 and gNB 702. The flow of uplink CG is shown at 750 between UE 751 and gNB 752.

[0109] The timing of SPS / CG can be proactively adjusted by RRC signaling, as described below.

[0110] In one example, this can be done using existing RRC signaling to configure CG / SPS. For example, SPS-Config for DL SPS and ConfiguredGrantConfig for UL CG. In another example, this can be done using a new type of RRC message, which can include:

[0111] • timeDomainAllocation: indicates the combination of starting symbol and length and PUSCH mapping type, see TS 38.214

[19] , clause 6.1.2 and TS 38.212

[17] , clause 7.3.1.

[0112] • timeDomainOffset: offset related to SFN = 0, see TS 38.321 [3], clause 5.8.2.

[0113] • For DL SPS transmission, CMI (number of transmission intervals / periods based on 5G system clock or rate ratio) can also be included.

[0114] Before the timing adjustment (i.e., advance or delay τ adj ) takes effect, the current SPS / CG can continue with the same period T, as shown in 710 and 760 in Figure 7

[0115] ​Figures 8(a) and 8(b) show the effectiveness of timing adjustment in mitigating clock mismatch issues. In Figure 8(a), the clock mismatch is +32ppm, and in Figure 8(b), the clock mismatch is -32ppm. The dotted line represents the result without timing adjustment, for comparison. In both example cases, the latency is improved when using the timing adjustment method described herein. Figure 9 The simulation parameters used are shown.

[0116] The operation of each network entity described above will now be summarised.

[0117] RAN side: Operation of a base station (e.g., gNB)

[0118] For DL SPS, the CMI is provided by the gNB to the UE device (based on the 5G system clock and / or rate ratio described above, in the form of number of transmission intervals / periods). The CMI can be provided to the UE as follows:

[0119] a. In the SPS configuration RRC;

[0120] b. In another type of RRC signalling.

[0121] The proposed timing adjustment algorithm is then run. This can include the following steps: determining timing adjustment parameters (e.g. high / low thresholds); calculating a timing adjustment factor; and performing a timing adjustment action.

[0122] Timing adjustment can be done in the following ways:

[0123] Passive SPS / CG timing adjustment with PDCCH:

[0124] - With existing DCI format.

[0125] - With another type of DCI format.

[0126] - The timing adjustment DCI can be scrambled by the CS-RNTI identifying the SPS / CG.

[0127] Active SPS / CG timing adjustment with RRC signalling:

[0128] - With existing SPS configuration RRC.

[0129] - With another type of SPS.

[0130] For UL CG, the CMI obtained from the UE is also provided to the UPF in the core network. This can be provided by another core network component, such as a session management function (SMF) component.

[0131] The gNB can also measure the CMI and jitter of data flow from the core network, and keep and forward periodic data burst from the core network to eliminate jitter.

[0132] Thus, the gNB can be used to provide timing adjustment command to the UE with DCI format or RRC signaling. For UL CG, the gNB can be used to further provide the CMI obtained from the UE to the UPF in the core network. This can be provided by another core network component, e.g. SMF component. For passive timing adjustment, the gNB can decide whether to adjust the timing of the next data packet transmission, and indicate in the DCI. This can be done using a new type of DCI, which includes at least the information of the time domain resource for the next transmission after adjustment. For active timing adjustment, the gNB can calculate the number of future CG / SPS periods when the timing adjustment should be made, and indicate in the RRC message. This can be done using a new type of RRC, which includes at least the information of the time domain resource for the future transmission after adjustment.

[0133] UE device side

[0134] For UL CG, the UE is used to measure the CMI from external network nodes or end stations.

[0135] For UL CG, the UE device provides the CMI to the gNB (e.g. in MAC CE).

[0136] For UL CG, the UE device provides the holding time of data burst at the UE to the gNB (e.g. with MAC CE or attached to the data burst). The holding time can be quantized to reduce UL overhead.

[0137] For UL CG, the timing of CG transmission is adjusted according to the timing adjustment command (PDCCH / DCI or RRC signaling) from the gNB.

[0138] For DL SPS, the data burst is output (egress) according to the CMI provided by the gNB to the UE device.

[0139] Thus, the UE can measure the CMI from external network nodes and provide the CMI to the gNB, provide the holding time to the gNB, and adjust the transmission timing in UL CG according to the timing adjustment command from the gNB.

[0140] Core network (or components thereof)

[0141] For DL SPS, the core network (e.g. UPF) measures the CMI from external network nodes or end stations.

[0142] The measured CMI is provided from the core network to the gNB. For example, the CMI (e.g., rate ratio) can be added to time sensitive communication assistant information (TSCAI).

[0143] For UL CG traffic, data bursts are output according to the CMI provided by the gNB.

[0144] Accordingly, the core network can measure CMI from an external network node and provide the CMI to the gNB. This can be provided by another core network component, such as a SMF component. For UL CG, the core network can output data bursts according to the CMI provided by the gNB.

[0145] In the foregoing overview, the specific terminology UE device can be replaced by any suitable communication terminal or UE device, the specific terminology gNB can be replaced by any suitable base station, access node or network node, and the specific terminology core network (or specific components thereof, such as UPF) can be replaced by any suitable network node.

[0146] Using the methods described herein, the timing of outgoing data streams can be adjusted to mitigate mismatches between clocks of different domains.

[0147] Applicant hereby discloses the subject matter of this application alone, as well as in any possible combination with two or more of such subject matter, even if such combinations are not explicitly disclosed herein, solely to the extent that such combinations are within the purview of one of ordinary skill in the art, upon reading the foregoing disclosure, and that such combinations do not depart from the scope of the present application as defined by the claims. Applicant hereby asserts that aspects of the present application can comprise any such individual feature or combination of features. In view of the description herein, various modifications will be apparent to those skilled in the art.

Claims

1. A communication terminal, characterized by comprising: For supporting a periodic data flow by forwarding messages received from a communication network to an external node that is not synchronized with the communication network, the communication terminal is configured to: obtain one or more timing adjustment indications from an access node of the communication network; adjust a transmission timing of the periodic data flow in accordance with the one or more timing adjustment indications; wherein the one or more timing adjustment indications are based on clock mismatch information between the communication terminal and the external node and a holdover time, the holdover time being a time elapsed between a data packet arriving at the communication terminal and the communication terminal transmitting the data packet; wherein the clock mismatch information is determined based on: (i) a number of cycles in which the communication network transmits and receives messages of the periodic data flow in accordance with a frequency of an internal clock of the communication network; (ii) a ratio of a frequency of a clock of the external node to a frequency of the internal clock of the communication network, wherein the ratio of frequencies is directly measured in terms of an arrival time of a data burst or data packet; wherein the communication terminal is further configured to: estimate the clock mismatch information between the communication terminal and the external node; and provide the estimated clock mismatch information and the holdover time to the access node of the communication network for providing the estimated clock mismatch information to a session management function, SMF, of the communication network via time sensitive communication assistance information, TSCAI, of the access node of the communication network; wherein the communication terminal is configured to quantify the holdover time and report the holdover time to the access node.

2. The communication terminal according to claim 1, characterized by The communication terminal is a user equipment and the access node is a nodeB.

3. An access node, characterized by For operating in a communication network to support a periodic data flow by forwarding messages received by the access node from another node of the network to a communication terminal, the access node is configured to receive clock mismatch information between the communication terminal and an external node from the communication terminal; and to perform the following: (a) sending a timing adjustment command to the communication terminal, wherein the timing adjustment command is based on the clock mismatch information and a holdover time, the holdover time being a time elapsed between a data packet arriving at the communication terminal and the communication terminal transmitting the data packet; (b) providing the clock mismatch information to a session management function, SMF, of the communication network via time sensitive communication assistance information, TSCAI; and (c) adjusting a timing of the periodic data flow to the communication terminal in accordance with the clock mismatch information; wherein the clock mismatch information is determined based on: (i) a number of cycles in which the communication network transmits and receives messages of the periodic data flow in accordance with a frequency of an internal clock of the communication network; (ii) a ratio of a frequency of a clock of the external node to a frequency of the internal clock of the communication network, wherein the ratio of frequencies is directly measured in terms of an arrival time of a data burst or data packet.

4. The access node of claim 3, wherein, The access node is configured to adjust a timing of transmitting a subsequent data packet of the periodic data flow and to indicate the timing adjustment to the communication terminal.

5. The access node of claim 3, wherein, The access node is configured to determine a number of future periods in which the timing of transmission of packets of the periodic data stream should be adjusted and to indicate the number of periods to the communication terminal.

6. The access node of any one of claims 3 to 5, wherein, The other node is part of a core network, the access node is a nodeB and the communication terminal is a user equipment.

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