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EP-4349085-B1 - IMPROVING TIME SYNCHRONIZATION ACCURACY IN A WIRELESS NETWORK

EP4349085B1EP 4349085 B1EP4349085 B1EP 4349085B1EP-4349085-B1

Inventors

  • PATEL, Dhruvin
  • DIACHINA, JOHN WALTER

Dates

Publication Date
20260506
Application Date
20220603

Claims (16)

  1. A method for a controller of a plurality of user equipment, UEs, that are served by a radio access network, RAN, node, the method comprising: receiving (810) information about the following from each of the UEs: first measurements, UE DL,Rx , of respective timing events of the radio link between the UE and the RAN node; and second measurements, UE RxTxDiff , of respective time differences between the UE receiving a downlink, DL, reference signal, RS, and transmitting a corresponding uplink, UL, RS; based on the received information, selecting (820) one of the plurality of UEs to provide a time-sensitive network, TSN, end station with a TSN message timestamped by a system clock time that is associated with the RAN and that is based on at least one first measurement and at least one second measurement.
  2. The method of claim 1, wherein selecting (820) one of the plurality of UEs comprises: determining (822) which of the plurality of UEs has least variability in the first measurements and the second measurements; and selecting (823) the UE having least variability to provide the system clock time associated with the RAN to the TSN end station.
  3. The method of claim 2, wherein, for each of the UEs, the received information about the first measurements comprises a first variability of the first measurements and the received information about the second measurements comprises a second variability of the second measurements.
  4. The method of claim 2, wherein: for each of the UEs, the received information about the first measurements comprises a plurality of the first measurements and the received information about the second measurements comprises a plurality of the second measurements; and selecting (820) one of the plurality of UEs further comprises determining (821), for each of the UEs, a first variability of the plurality of the first measurements and a second variability of the plurality of the second measurements.
  5. The method of any of any of claims 1-4, wherein the timing events are ends of frames identified by respective system frame numbers, SFNs, in timing messages from the RAN node.
  6. The method of any of claims 1-5, further comprising sending (830), to the selected UE, an indication for the selected UE to provide the TSN end station with a TSN message timestamped by the system clock time.
  7. A method for a user equipment, UE, configured to operate in a radio access network, RAN, as one of a plurality of UEs coupled to a time sensitive network, TSN, end station, the method comprising: performing (910) the following measurements: first measurements, UE DL,Rx , of respective timing events of the radio link between the UE and a RAN node; and second measurements, UE RxTxDiff , of respective time differences between the UE receiving a downlink, DL, reference signal, RS, and transmitting a corresponding uplink, UL, RS; sending (930) information about the first measurements and information about the second measurements to a controller of the plurality of UEs; and based on an indication received from the controller, providing (995) the TSN end station with a TSN message timestamped by a system clock time that is associated with the RAN and that is based on at least one first measurement and on at least one second measurement.
  8. The method of claim 7, wherein the information about the first measurements comprises a plurality of the first measurements and the information about the second measurements comprises a plurality of the second measurements.
  9. The method of claim 7, wherein: the method further comprises determining a first variability of a plurality of the first measurements and a second variability of a plurality of the second measurements; and the information about the first measurements comprises the first variability and the information about the second measurements comprises the second variability.
  10. The method of any of any of claims 7-9, wherein the timing events are ends of frames identified by respective system frame numbers, SFNs, in timing messages from the RAN node.
  11. The method of any of claims 7-10, further comprising: receiving (960), from the RAN node, an indication of a system clock time associated with the RAN; receiving (970) the TSN message from the RAN node, wherein the TSN message indicates a time associated with a grandmaster clock of the TSN, TSN GM; and timestamping (990) the TSN message based on the following: the indicated system clock time, and at least one first measurement.
  12. The method of claim 11, further comprising sending (940) the second measurements to the RAN node, wherein the system clock time received from the RAN node is compensated for DL propagation delay, PD, based on at least one second measurement.
  13. The method of claim 11, further comprising: receiving (950), from the RAN node, one or more third measurements, gNB RxTxDiff , of respective time differences between the RAN node receiving an UL RS and transmitting a corresponding DL RS; and compensating (980) the indicated system clock time for DL propagation delay based on at least one second measurement and at least one third measurement, wherein timestamping (990) the TSN message is based on the compensated system clock time and the at least one first measurement.
  14. The method of any of claims 7-13, wherein the indication is received from the controller in response to sending (930) the information about the first measurements and the information about the second measurements.
  15. A controller (710, 1014) for a plurality of user equipment, UEs (310, 510, 620, 630, 720, 730, 1012, 1100) that are served by a radio access network, RAN, node (520, 640, 740, 1010, 1200), the controller being configured to: receive information about the following from each of the UEs: first measurements, UE DL,Rx , of respective timing events of the radio link between the UE and the RAN node; and second measurements, UE RxTxDiff , of respective time differences between the UE receiving a downlink, DL, reference signal, RS, and transmitting a corresponding uplink, UL, RS; based on the received information, select one of the plurality of UEs to provide a time-sensitive network, TSN, end station (550, 650, 750) with a TSN message timestamped by a system clock time that is associated with the RAN and that is based on at least one first measurement and at least one second measurement.
  16. A user equipment, UE (310, 510, 620, 630, 720, 730, 1012, 1100) configured to operate in a radio access network, RAN (398, 1004) as one of a plurality of UEs coupled to a time sensitive network, TSN, end station (550, 650, 750), the UE being configured to: perform the following measurements: first measurements, UE DL,Rx , of respective timing events of the radio link between the UE and a RAN node (520, 640, 740, 1010, 1200); and second measurements, UE RxTxDiff , of respective time differences between the UE receiving a downlink, DL, reference signal, RS, and transmitting a corresponding uplink, UL, RS; send information about the first measurements and information about the second measurements to a controller (710, 1014) for the plurality of UEs; and based on an indication received from the controller, provide the TSN end station with a TSN message timestamped by a system clock time that is associated with the RAN and that is based on at least one first measurement and on at least one second measurement.

Description

TECHNICAL FIELD The present application relates generally to the field of wireless networks and more specifically to techniques for improving time synchronization accuracy in a wireless network, such as when a wireless network and a wireless device are utilized to deliver highly accurate timing information from a time-sensitive network (TSN). BACKGROUND Industry 4.0 is a term that often refers to automation and data exchange in manufacturing. It can include concepts and/or technologies such as cyber-physical systems, the Internet of Things (IoT), cloud computing, and cognitive computing. Industry 4.0 is also referred to as the fourth industrial revolution or "I4.0" for short. One scenario or use case for Industry 4.0 is the so-called "smart factory". Within modular structured smart factories, cyber-physical systems monitor physical processes, create a virtual copy of the physical world, and make decentralized decisions. Over the Internet of Things (IoT), cyber-physical systems communicate and cooperate with each other, and with humans, in real-time both internally and across organizational services offered and used by participants of a value chain of which the smart factory is a part. Such smart factory environment environments are also referred to as Industrial Internet of Things (IIoT). There are four common principles associated with Industry 4.0. First, "interoperability" requires the ability to connect machines, devices, sensors, and people to communicate with each other via the IoT or, alternatively, the "Internet of People" (IoP). Second, "information transparency" requires information systems to have the ability to create a virtual copy of the physical world by enriching digital models (e.g., of a smart factory) actual with sensor data. For example, this can require the ability to aggregate raw sensor data to higher-value context information. Third, "technical assistance" requires assistance systems to be able to support humans by aggregating and visualizing information comprehensively for making informed decisions and solving urgent problems on short notice. This principle can also refer to the ability of cyber physical systems to physically support humans by conducting a range of tasks that are unpleasant, too exhausting, or unsafe for their human co-workers. Finally, cyber physical systems should have the ability to make decentralized decisions and to perform their tasks as autonomously as possible. In other words, only in the case of exceptions, interferences, or conflicting goals, should tasks be delegated to a higher level. These principles associated with Industry 4.0 support various use cases that place many requirements on a network infrastructure. Use cases include simpler ones such as plant measurement to more difficult ones such as precise motion control in a robotized factory cell. To address these requirements, the IEEE 802.1 working group (particularly, task group TSN) has developed a Time Sensitive Networking (TSN) standard. TSN is based on the IEEE 802.3 Ethernet standard, a wired communication standard that is designed for "best effort" quality of service (QoS). TSN describes a collection of features intended to make legacy Ethernet performance more deterministic, including time synchronization, guaranteed low-latency transmissions, and improved reliability. The TSN features available today can be grouped into the following categories (shown below with associated IEEE specifications): Time Synchronization (e.g., IEEE 802.1AS);Bounded Low Latency (e.g., IEEE 802.1Qav, IEEE 802.1Qbu, IEEE 802.1Qbv, IEEE 802.1Qch, IEEE 802.1Qcr);Ultra-Reliability (e.g., IEEE 802.1CB, IEEE 802.1Qca, IEEE 802.1Qci);Network Configuration and Management (e.g., IEEE 802.1Qat, IEEE 802.1Qcc, IEEE 802.1Qcp, IEEE 802.1CS). Figures 1-2 are block diagrams that respectively illustrate Centralized and Fully Centralized TSN configuration models, as specified in IEEE Std. 802.1Qbv-2015. Within a TSN network, the communication endpoints are called "Talker" and "Listener." All the switches and/or bridges between a Talker and a Listener must support certain TSN features, such as IEEE 802.1AS time synchronization. A "TSN domain" includes all nodes that are synchronized in the network, and TSN communication is only possible within such a TSN domain. The communication between Talker and Listener is in streams. Each stream is based on data rate and latency requirements of an application implemented at both Talker and Listener. A Talker initializes a stream towards a Listener, and the TSN configuration and management features are used to set up the stream and to guarantee the stream's requirements across the network. Some TSN features require a central management entity called Centralized Network Configuration (CNC), as shown in Figure 1. The CNC can use, for example, Netconf and YANG models to configure the switches in the network for each TSN stream. This also facilitates the use of time-gated queueing (defined in IEEE 8