WO2019201438A1 - Techniques de synchronisation temporelle à commande réseau pour une communication de liaison latérale et/ou de liaison montante d'ue - Google Patents

Techniques de synchronisation temporelle à commande réseau pour une communication de liaison latérale et/ou de liaison montante d'ue Download PDF

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Publication number
WO2019201438A1
WO2019201438A1 PCT/EP2018/059916 EP2018059916W WO2019201438A1 WO 2019201438 A1 WO2019201438 A1 WO 2019201438A1 EP 2018059916 W EP2018059916 W EP 2018059916W WO 2019201438 A1 WO2019201438 A1 WO 2019201438A1
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WIPO (PCT)
Prior art keywords
synchronization
base station
delay
time
time reference
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PCT/EP2018/059916
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English (en)
Inventor
Konstantinos MANOLAKIS
Markus Martin DILLINGER
Wen Xu
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Huawei Technologies Duesseldorf Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Huawei Technologies Duesseldorf Gmbh filed Critical Huawei Technologies Duesseldorf Gmbh
Priority to PCT/EP2018/059916 priority Critical patent/WO2019201438A1/fr
Priority to CN201880092504.7A priority patent/CN111989960B/zh
Publication of WO2019201438A1 publication Critical patent/WO2019201438A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H04W56/0015—Synchronization between nodes one node acting as a reference for the others
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
    • H04W56/005—Synchronisation arrangements compensating for timing error of reception due to propagation delay compensating for timing error by adjustment in the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H04J3/0658—Clock or time synchronisation among packet nodes
    • H04J3/0661—Clock or time synchronisation among packet nodes using timestamps
    • H04J3/0667—Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays

Definitions

  • the disclosure relates to techniques for network-based time synchronization for UE sidelink and/or uplink communication, in particular for inter-operator sidelink and/or uplink communication.
  • the disclosure particularly relates to a base station, in particular an eNodeB or a gNodeB, for synchronizing at least one user equipment, UE, for its uplink and/or sidelink communication.
  • the disclosure further relates to corresponding UEs, time reference server and synchronizing methods.
  • Device-to-device (D2D) communication is considered as a key component for future 5G networks, mainly in the context of vehicle-to-anything (V2X) communications.
  • V2X vehicle-to-anything
  • the nature of V2X communication requires communication between users assigned to different base stations, i.e. multi-cellular V2V, which users may even belong to different mobile network operators (MNOs).
  • MNOs mobile network operators
  • a global time reference serving as a common beckon of time is required for all mobile users.
  • sidelink time synchronization as for example provided by the cellular network or mutually achieved between the users can be performed and refined. Since time references provided by the base station to mobile users for cellular (uplink/downlink) transmission are in general different, these cannot directly serve as a reference for the sidelink, which is why a global reference is needed at first place. Moreover, it is noted that external sources as GNSS references are not always available and cannot be used as a main global reference for V2V/D2D communication. SUMMARY
  • a new procedure for distributing a global time reference from a remote network entity (e.g. cloud server) through the MNO core and access network until the mobile user is presented.
  • the procedure uses basic parts of the IEEE 1588 protocol to estimate and compensate the time offset between a mobile user and the cloud server and measure the delay.
  • attached mobile users report certain measurements back to their base station and receive instructions in the form of control information regarding the time reference to use for the sidelink and/or the uplink.
  • all users including the ones assigned to different MNOs, reach a common time perception, which they can follow for the V2V sidelink or uplink, and based on which they can receive further instructions or perform mutual synchronization to align their sidelink or uplink transmissions in time. While the focus lies on UE’s sidelink communication, the concepts can be used as well for the UE’s uplink communication.
  • the scope of the disclosure is the definition of a procedure for remote network-based time synchronization, used for sidelink communication between UEs of same or different MNOs.
  • a basic idea of this disclosure is the introduction of new signaling and information/measurement exchange between a UE and its eNB, while in parallel a PTP is executed between the UE and a remote server used for sidelink coordination.
  • signaling is extended to include out-of-coverage UEs in order to synchronize them and allow for synchronized sidelink transmission, e.g. in partial cellular coverage scenarios.
  • Different implementations regarding the protocol stack implementation and aspects of the UE internal architecture are also discussed and solutions are presented. In order to describe the invention in detail, the following terms, abbreviations and notations will be used:
  • DL Downlink, i.e. link from network to UE
  • UL Uplink, i.e. link from UE to network
  • SL Sidelink, i.e. link between UEs
  • UE User Equipment
  • BS Base Station, eNodeB
  • C-server Cloud server or central server
  • D2D Device-to-device
  • V2X Vehicle-to-anything
  • MNO Mobile Network Operator
  • the invention relates to a base station, in particular an eNodeB or a gNodeB, for synchronizing at least one user equipment, UE , for its uplink and/or sidelink communication
  • the base station comprising a processor configured to: forward at least one time synchronization message of a time synchronization protocol, in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP, between a time reference server and at least one UE; receive synchronization information of the at least one UE about the synchronization between the at least one UE and the time reference server, in particular a time offset and an end-to-end delay between the time reference server and the at least one UE; and transmit a synchronization instruction to the at least one UE.
  • a time synchronization protocol in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP
  • Such a base station improves communication, in particular UE sidelink and/or uplink communication in mobile communication networks, in particular 5G networks.
  • the base station thus guarantees reliable communication and fast link establishment.
  • a common perception of time can be achieved, in particular a common time reference can be provided to all mobile users involved in mobile communication.
  • the base station is enabled to acquire synchronization information about the time reference server and/or an end-to-end delay. Further advantages are that the base station enables the at least one UE synchronizing with the time reference server; and UEs’ uplink and/or sidelink communication follow a time reference based on the time reference server and are time-aligned/synchronized with each other.
  • the BS does not need to synchronize with the time reference server as well, but this can be an optional feature.
  • the time reference finally used by the UEs does not need to be the server reference, but is based/depending on it.
  • the processor is configured to use a second time reference, which is not based on a time reference of the time reference server, for synchronization of downlink communication with the at least one UE.
  • This provides the advantage that synchronization of UE’s downlink communication is independent from synchronization of UEs’ uplink and/or sidelink communication.
  • the base station is configured to use alternatively a time reference depending on the time reference server for synchronizing of downlink communication with the at least one UE.
  • This provides the advantage that synchronization of UE’s downlink communication is dependent on synchronization of UEs’ uplink and/or sidelink communication.
  • the synchronization information, in particular the time offset and end-to-end delay, between the time reference server and the at least one UE is based on an offset between the time reference server and the at least one UE and a delay from the time reference server to the at least one UE and/or a delay from the at least one UE to the time reference server.
  • the term“based on” can be in particular an average, e.g. a weighted average, between delays in different directions and/or from more than one UEs.
  • the processor is configured to determine an access delay between the base station and the at least one UE. This provides the advantage that synchronization can be improved when determining the access delay between BS and UE.
  • the processor is configured to determine the access delay between the base station and the at least one UE based on UE-specific information provided by the at least one UE, in particular depending on radio propagation delay, known contribution of the base station to the access delay and timing advance, TA.
  • the processor is configured to determine a network delay between the time reference server and the base station based on the synchronization information, in particular the end-to-end delay, and the access delay.
  • the base station is configured to use the network delay for synchronization of the at least one UE.
  • This provides the advantage that synchronization can be improved when utilizing the network delay for synchronization of the UE.
  • the processor is configured to determine the time reference of the time reference server based on the network delay.
  • This provides the advantage that determining the time reference of the time reference server can be improved when determining it based on the network delay.
  • the processor is configured to transmit synchronization instructions to a plurality of UEs, and in particular wherein the synchronization instructions are UE-specific or specific to a group of UEs. This provides the advantage that specific synchronization can be transmitted to all UEs. Hence synchronization can be optimized for each UE.
  • the synchronization instructions are based on the network delay and UE-specific time measurements and parameters, in particular access delay, radio propagation delay and known contribution of the base station to the access delay and UE-specific timing advance, TA.
  • the processor is configured to forward the at least one time synchronization message between the time reference server and the at least one UE without participating in the time synchronization protocol.
  • the term“without participating in the time synchronization protocol” in the sense of the invention comprises that the BS does not implement the synchronization protocol itself and takes a role within the communication according to this protocol, and/or that the BS does not read the time synchronization message.
  • the processor is configured to prioritize forwarding the at least one time synchronization message between the time reference server and the at least one UE.
  • the processor is configured to request the at least one UE providing the synchronization information, in particular the end-to-end delay, between the time reference server and the at least one UE. This provides the advantage that if the base station realizes that the synchronization should be updated it can request so.
  • the synchronization information, in particular the end-to-end delay, between the time reference server and the at least one UE is periodically received from the at least one UE.
  • the processor is configured to request the at least one UE changing a period for reporting the synchronization information, in particular the end-to-end delay, in particular if the base station detects changes in network delay between the time reference server and the base station.
  • the invention relates to a user equipment, UE, for assisting a base station for synchronizing at least one user equipment, UE, for its uplink and/or sidelink communication, the UE comprising a processor configured to: receive a time synchronization message of a time synchronization protocol, in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP, from a time reference server;
  • a time synchronization protocol in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP
  • synchronization information about a synchronization between the UE and the time reference server in particular a time offset and an end-to-end delay between the time reference server and the UE, based on the time synchronization message; report the synchronization information to the base station; and receive a synchronization instruction from the base station for synchronizing the UE’s uplink and/or sidelink communication.
  • Such a UE improves communication, in particular UE sidelink and/or uplink
  • the UE thus can guarantee reliable communication and fast link establishment.
  • a common perception of time can be achieved, in particular a common time reference can be provided to all mobile users involved in mobile communication.
  • the UE is enabled synchronizing with the time reference server; and UEs’ uplink and/or sidelink communication follow a time reference based on the time reference server and are time-aligned/synchronized with each other.
  • the UE is configured to receive and/or report the time synchronization message, the synchronization information, and/or synchronization instruction through another UE.
  • the UE can be out-of-coverage and communicates with the time reference server and/or the base station via second UE that is in-coverage.
  • the second UE operates as relay node for the respective functionality then.
  • the processor is configured to report the synchronization information to the base station via an Uplink feedback channel.
  • the processor is configured to receive the UE-specific synchronization instructions from the base station via a Downlink control channel.
  • This provides the advantage that a standard channel such as the DL control channel that is already available can be used for receiving the synchronization instructions.
  • the processor can be configured to align a clock offset with the time reference server based on a first synchronization message received from the time reference server and particularly based on a first follow-up message to the first synchronization message according to the PTP/NTP protocol.
  • the processor can be configured to determine a master-to-slave delay indicating a delay between the time reference server and the UE based on the aligned clock offset and a second synchronization message received from the time reference server and particularly based on a second follow-up message to the second synchronization message according to the PTP/NTP protocol.
  • the processor can be configured to determine a slave-to-master delay indicating a delay between the UE and the time reference server based on a delay response message received from the time reference server and in particular based on a follow-up message to the delay response message according to the PTP/NTP protocol.
  • the first synchronization message, the second synchronization message and the delay response message can be received from the time reference server without modification by the base station message according to the PTP/NTP protocol.
  • the UE comprises: a first modem comprising a first protocol stack, PC5, for processing the UE’s sidelink communication; and a second modem comprising a second protocol stack, Uu for processing Uplink/Downlink communication with the base station, wherein the first protocol stack and the second protocol stack comprise a shared IP layer, a shared Radio Resource Connection, RRC, layer and separate MAC layers.
  • the processor is configured to process the time synchronization protocol based on the shared IP layer and to synchronize the UE’s uplink and/or sidelink communication based on the shared RRC layer or based on the separate MAC layers.
  • the processor is configured to
  • the processor is configured to report the synchronization information to the base station, wherein the synchronization information includes an internal delay between the first modem and the second modem.
  • This provides the advantage that by reporting the internal delay to the base station, the base station can increase synchronization accuracy.
  • the processor is configured to provide a synchronization instruction to another UE that is out of coverage from the base station.
  • the processor is configured to provide the synchronization instruction to the other UE via a sidelink control channel between the UE and the other UE.
  • the synchronization information provided to the other UE can be specific for the other UE. This provides the advantage that the out-of-coverage UE can be efficiently synchronized via the sidelink control channel to the (in-coverage) UE.
  • the UE is configured to measure a delay, in particular a round-trip delay, between the UE and the other UE and to base the synchronization instruction on this delay.
  • This provides the advantage that synchronization of the out-of-coverage UE can be improved when synchronization is based on the round-trip delay between the UE and the other UE.
  • the UE is configured to receive a request from the other UE to measure the delay.
  • the invention relates to a time reference server for
  • the time reference server comprising a processor configured to: transmit at least one time synchronization message of a time synchronization protocol, in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP, to the at least one UE, wherein the at least one synchronization message comprises information to enable the at least one UE to report synchronization information about a synchronization between the at least one UE and the time reference server, in particular an end-to-end delay between the time reference server and the at least one UE.
  • a time synchronization protocol in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP
  • Such a time reference server provides the advantage that the UE can then be configured to report the synchronization information to a base station to enable the base station transmitting a synchronization instruction to the at least one UE for synchronizing the UE’s uplink and/or sidelink communication.
  • a time reference server also referred to as C-server, improves communication, in particular UE sidelink and/or uplink communication in mobile communication networks, in particular 5G networks.
  • the time reference server can provide reliable communication and fast link establishment. By applying such time reference server, a common perception of time can be achieved, in particular a common time reference can be provided to all mobile users involved in mobile communication.
  • time reference server enables the at least one UE synchronizing with the time reference server; and UEs’ uplink and/or sidelink communication follow a time reference based on the time reference server and are time- aligned/synchronized with each other.
  • the processor is configured to do at least one of the following: transmit a first synchronization message and particularly a first follow-up message to the first synchronization message via bypassing the base station to the UE; transmit a second synchronization message and particularly a second follow-up message to the second synchronization message via bypassing the base station to the UE; receive a delay request message via bypassing the base station from the UE; and transmit a delay response message and particularly a follow-up message to the delay response message via bypassing the base station to the UE.
  • the time reference server is configured to transmit the time synchronization message to a plurality of operator networks; and/or to be operated extern of an operator network.
  • the invention relates to a method for synchronizing user equipment, UE, for its uplink and/or sidelink communication, the method comprising:
  • a time synchronization protocol in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP
  • PTP Precision Time Protocol
  • NTP Network Timing Protocol
  • Such a method that can be implemented at BS site improves communication, in particular UE sidelink and/or uplink communication in mobile communication networks, in particular 5G networks.
  • the method thus guarantees reliable communication and fast link establishment.
  • a common perception of time can be achieved, in particular a common time reference can be provided to all mobile users involved in mobile communication.
  • the invention relates to a method for synchronizing at least one user equipment, UE, for its uplink and/or sidelink communication, the method comprising: receiving a time synchronization message of a time synchronization protocol, in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP, from a time reference server; determining synchronization information about a synchronization between the UE and the time reference server, in particular an end-to-end delay between the time reference server and the UE, based on the time synchronization message; reporting the synchronization information to a base station; and receiving a synchronization instruction from the base station for synchronizing the UE’s uplink and/or sidelink communication.
  • a time synchronization protocol in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP
  • Such a method that can be implemented at UE site improves communication, in particular UE sidelink and/or uplink communication in mobile communication networks, in particular 5G networks.
  • the method thus guarantees reliable communication and fast link establishment.
  • a common perception of time can be achieved, in particular a common time reference can be provided to all mobile users involved in mobile communication.
  • Fig. 1 shows a schematic diagram illustrating an exemplary mobile (vehicular) network 100 with in-cellular coverage users 101 , 102 and out-of-cellular coverage users 103, 104;
  • Fig. 2 shows a schematic diagram illustrating a centralized C-Server architecture 200 according to the disclosure;
  • Fig. 3 shows a schematic diagram illustrating a C-Server architecture 300 according to the disclosure and sources of delay and time offset for the general scenario of multiple operators;
  • Fig. 4a shows a schematic diagram illustrating a delay measurement 400a in NTP/PTP based on one-step messaging
  • Fig. 4b shows a schematic diagram illustrating a delay measurement 400a in NTP/PTP based on two-step messaging
  • Fig. 5 shows a message sequence chart 500 illustrating the main steps of the IEEE 1588 time synchronization protocol
  • Fig. 6 shows a schematic diagram illustrating an exemplary mobile (vehicular) network 600 with synchronized sidelink 601 according to the disclosure
  • Fig. 7 shows a message sequence chart 700 illustrating signalling and operations between C-server, base station/eNB and mobile user/UE according to the disclosure
  • Fig. 8 shows a message sequence chart 800 illustrating the principle of transparent clock according to the disclosure
  • Fig. 9 shows a message sequence chart 900 illustrating synchronization of UEs without cellular coverage according to the disclosure
  • Fig. 10 shows a schematic diagram illustrating an exemplary implementation of protocol stacks in a mobile (vehicular) network including C-server, base station/eNB and UE according to a first implementation form
  • Fig. 11 shows a schematic diagram illustrating an exemplary implementation of protocol stacks 1000 in a mobile (vehicular) network including C-server 232, base station/eNB 211 and UE 201 according to a second implementation form;
  • Fig. 12 shows a schematic diagram illustrating an exemplary implementation of clock distribution within the UE according to the disclosure
  • Fig. 13 shows a schematic diagram illustrating a method 1300 for synchronizing a UE 201 for its uplink and/or sidelink communication, from base station 21 1 side, according to the disclosure.
  • Fig. 14 shows a schematic diagram illustrating a method 1400 for synchronizing a UE 201 for its uplink and/or sidelink communication, from UE 201 side, according to the disclosure
  • the methods and devices described herein may also be implemented in wireless communication networks, in particular communication networks using WiFi communication standards according to IEEE 802.1 1 and higher.
  • the described devices may include integrated circuits and/or passives and may be manufactured according to various technologies.
  • the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives.
  • Radio signals may be or may include radio frequency signals radiated by a radio transmitting device (or radio transmitter or sender) with a radio frequency lying in a range of about 3 kHz to 300 GHz.
  • processors may include processors, memories and transceivers, i.e. transmitters and/or receivers.
  • processor describes any device that can be utilized for processing specific tasks (or blocks or steps).
  • a processor can be a single processor or a multi-core processor or can include a set of processors or can include means for processing.
  • a processor can process software or firmware or applications etc.
  • a base station may include access nodes, evolved NodeBs (eNBs), gNBs, NodeBs, master eNBs (MeNBs), secondary eNBs (SeNBs), remote radio heads and access points.
  • eNBs evolved NodeBs
  • gNBs evolved NodeBs
  • NodeBs NodeBs
  • MeNBs master eNBs
  • SeNBs secondary eNBs
  • Fig. 1 shows a schematic diagram illustrating an exemplary mobile (vehicular) network 100 with in-cellular coverage users 101 , 102 and out-of-cellular coverage users 103, 104.
  • An exemplary number of five UEs 101 , 102, 103, 104, 105 is shown (there may be more or less UEs) from which two UEs 101 , 102 are in-cellular coverage, UE 101 is in-cellular coverage 1 11 of eNodeB 110 and UE 102 is in-cellular coverage 121 of eNodeB 120.
  • first eNodeB 110 may be a base station of a first mobile network operator (MNO) while second eNodeB 120 may be a base station of a second MNO.
  • MNO mobile network operator
  • UEs 103, 104, 105 are out-of-cellular coverage, where UEs 103, 104 (and additionally UEs 101 , 102) are within communication area and also within synchronization area but only one UE 105 is within synchronization area but outside communication area. Note that these numbers are only meant as exemplary numbers, any other numbers can be used as well.
  • UEs 101 , 103 are equipped with a GNSS receiver for receiving timing information from a GNSS system 160 represented by a satellite.
  • UE 101 can be connected to eNB 1 10 and additionally to remote small cell unit (RSU) 130.
  • RSU remote small cell unit
  • FIG. 1 A typical scenario of a mobile (vehicular) network in a cellular environment is shown in Figure 1 , including in- and out-of cellular coverage mobile users with User Equipments (UEs) 102, 103, 104, 105, some of which (e.g. 101 , 103) are also equipped with a Global Navigation Satellite System (GNSS) 160 receiver.
  • UEs User Equipments
  • GNSS Global Navigation Satellite System
  • Coexistence of multiple sidelink transmissions - also between users of different MNOs- within one frequency band requires time alignment of transmitted signals to avoid interference; in case a sidelink frequency band shall be hosted within a cellular band used for UL/DL, further time alignment with respect to these cellular transmissions will be required.
  • Time alignment of users attached to different and non-synchronized base stations e.g. using Frequency Division Duplex (FDD) and/or assigned to different MNOs’ network;
  • FDD Frequency Division Duplex
  • GNSS-like time references GPS, Galileo etc.
  • Fig. 2 shows a schematic diagram illustrating a centralized C-Server architecture 200 according to the disclosure.
  • the communication system includes a central server 232, also referred to as cloud server 232 that may be located in the cloud 230.
  • the cloud server 232 also referred to as cloud server 232 that may be located in the cloud 230.
  • a first mobile user with first UE 201 may be connected to MN01 network 210, a second mobile user with second UE 202 may be connected to MN02 network 220 and a third mobile user with third UE 203 may be out-of-coverage but connected to first UE 201 via sidelink 204 connection.
  • First UE 201 and second UE 202 may be connected via sidelink 204 connection.
  • a central entity e.g. a central server (c-server) 232 is located inside or outside the MNOs’ core network (CN) or in the cloud 230, controls the sidelink 204 transmission between mobile users 201 , 202 attached to base stations 212, 222 of the same of different operators.
  • Multi-operator V2V is controlled by this c-server 232, which provides high-layer control of the UEs’ sidelink 204 in the form of control information 207, which is transmitted via each MNO’s core and access network 210, 220 to the UEs 201 , 202.
  • the role of the base stations 21 1 , 212 is to forward this control information 207 to their attached UEs 201 , 202 and to receive and forward feedback to the cloud server 232.
  • Control information 207 is transmitted from base stations 21 1 , 221 to UEs 201 , 202 in a dedicated channel within the downlink frequency band.
  • This architecture allows for using a shared band for V2V between all MNOs’ UEs 201 , 202, which has several benefits, e.g. allows for centralized resource management and resource allocation. Based on this architecture, a subset of MNO functionalities can be shifted to the central server 232.
  • Out- of-coverage UEs, e.g. 203 can further receive control information via sidelink 204 through in-coverage UEs, e.g. 201 .
  • Fig. 3 shows a schematic diagram illustrating a C-Server architecture 300 according to the disclosure and sources of delay and time offset for the general scenario of multiple operators.
  • the C-server architecture 300 of Fig. 3 is a similar representation of the C- server architecture 200 illustrated in Figure 2, in which time delays D ⁇ A 301 , D ⁇ b 302 between the C-server 232 and the base stations 21 1 , 221 of MN01 210 (denoted here as MNO A ) and MN02 220 (denoted here as MNOB) and time delays tm 304 and t R2 305 between the base stations 21 1 , 221 and their associated UEs 201 , 202 are highlighted.
  • time delays D ⁇ A 301 , D ⁇ b 302 between the C-server 232 and the base stations 21 1 , 221 of MN01 210 (denoted here as MNO A ) and MN02 220 (denoted here as MNOB) and time delays tm 304 and t R2
  • the sidelink transmission will be subject to several time offset and delay contributing factors, which are shown in the overview of Fig. 3.
  • the C-server 232 is assumed to use a global time reference t c , which can be provided by accurate GNSS, a highly-accurate local clock (rubidium or atomic clock) or other sources, and which is here considered as an ideal time reference.
  • Each base station see here two base stations 21 1 , 221 belonging to MNO A 210 and MNO B 220, are driven by local time references t A and t B , which are in the general case different to global time reference t c and have time offsets t A,off and t B, off with respect to the global reference t c .
  • these offsets include systematic offsets between different timing references used by c-server 232 and the particular eNB 21 1 , 221 , as well as timing errors due to clock drift or clock distribution effects within each MNOs’ network 210, 220.
  • MNOs are not aware of these offsets. This error model also applies to base stations of the same MNO.
  • a delay time At between c-server 232 and a particular base station 21 1 , 221 , which is in general unknown to the base station 21 1 , 221 and the MNO 210, 220.
  • the value of At may change, e.g. if the path (routers, gateway etc.) between c-server 232 and base station 21 1 , 221 changes.
  • SoTA State-of-the-Art
  • LTE and IEEE 802.1 1 p have to face very different and more relaxed synchronization requirements.
  • PHY-layer synchronization is performed by each UE through the detection of predefined synchronization sequences in DL with respect to the serving base station.
  • time advance is assigned to each UE by the network for aligning signals from different UEs. This level of PHY layer synchronization is sufficient for connection establishment with the base station.
  • the detection of synchronization signals provides time synchronization including BOF/BOS estimation as well as typically carrier frequency synchronization and user identification at the same time.
  • IEEE 802.1 1 p is by definition a non-synchronized system, in the sense that data is not transmitted in a predefined point in time and moreover spans the complete frequency band. Therefore, no mutual synchronization between users or global synchronization and time reference distribution is needed.
  • NTPs network timing protocols
  • PTPs Precision Time Protocols
  • IEEE 1588 and 1588-2008 also known as PTP Version 2
  • 4b and 5 are often used. These are used to synchronize clocks within a network and achieve accuracies in the sub-microsecond range. These protocols have been mainly designed for fixed network topologies, but are not common for dynamic wireless networks, as e.g. the cellular radio access network.
  • Fig. 4a shows a schematic diagram illustrating a delay measurement 400a in NTP/PTP based on one-step messaging.
  • the client 410 transmits a first message 401 at time ti to the server 420 which is received by the server 420 at time t 2 .
  • t 2 can be indicated by the server 420 as the timestamp of reception 403.
  • the server 420 transmits a second message 402 at time h to the client 410 which is received by the client 410 at time t 4 .
  • h can be indicated by the server 420 as the timestamp of transmission 404.
  • a round trip delay can be determined by the client 410 according to: round trip delay is equal to ((t 4 -t-i)- (t 3 -t 2 )).
  • One key point is the measurement of delay. This is achieved by exchange of packets including time stamps, i.e. the value the timer used when a particular event occurs.
  • the client 410 can use the time value provided by the server 420 and estimate the roundtrip delay (if the delays are symmetric, one-way delay is half of the round trip), e.g. according to the above-indexed formula which is shown in Fig. 4a.
  • Fig. 4b shows a schematic diagram illustrating a delay measurement 400a in NTP/PTP based on two-step messaging.
  • a master 430 transmits a first message 431 at time ti and a follow-up message 432 to the first message 431 to a slave 440.
  • the slave 440 knows the value of ti precisely, can determine the delay 433 between ti and reception of the follow-up message 432 precisely and can adjust its clock correspondingly.
  • Fig. 5 shows a message sequence chart 500 illustrating the main steps of the IEEE 1588 time synchronization protocol.
  • the ultimate goal of the PTP is to estimate and compensate the time offset with respect to a master 430 clock and network delay between master 430 and slave 440.
  • the main stages of the time synchronization protocol are the following.
  • Stage A, 510 clock offset alignment
  • the master 430 sends“sync” message 501 (at time ti) including timestamp and the slave 440 uses its local clock to timestamp the message arrival (at time t 2 ).
  • the slave 440 compares it to the actual sync transmission timestamp (at time ti) in master’s 430 follow-up message 502.
  • the difference between two timestamps (t 2 -t-i) equals to the clocks’ offset plus the transmission delay as illustrated at the bottom of Fig. 5.
  • Slave 440 receives a second sync/follow-up message set 503. Using its updated clock it calculates the master-to-slave delay d M ->s.
  • the slave 440 timestamps a delay request message 505 (at time t3).
  • the master 430 timestamps the arrival of the delay request message 505 (at time t 4 ) and sends back a delay response message 506.
  • the timestamps’ difference t3- U gives the slave-to-master delay ds->M.
  • the slave 440 averages the two directional delays and adjusts to the mean delay and offset, as shown at the bottom of Fig. 5.
  • Fig. 6 shows a schematic diagram illustrating an exemplary mobile (vehicular) network 600 with synchronized sidelink 601 according to the disclosure.
  • the mobile network 600 may correspond to the C-server architectures 200, 300 described above with respect to Figures 2 and 3.
  • PTP protocol messages 602 are exchanged between C-server 232 and respective UEs 201 , 202.
  • Control and feedback information 603 is exchanged between base stations 21 1 , 221 and corresponding UEs 201 , 202.
  • Sidelink information is exchanged via a synchronized Sidelink 601 between the UEs 201 , 202.
  • the PTP is implemented between the c-server 232 (that represents the master 430 according to Figures 4b and 5) and at least on UE (that represents the slave 440 according to Figures 4b and 5).
  • the time offset can be compensated and the end-to-end (E2E) delay can be measured by the UE 201 , 202.
  • the PTP packets subypass“ the base station 21 1 , 221 , meaning that it forwards PTP packets between c-server 232 and UE 201 , 202 without any need to read or modify them.
  • Fig. 7 shows a message sequence chart 700 illustrating signalling and operations between C-server, base station/eNB and mobile user/UE according to the disclosure.
  • the UE 201 reports measurements 701 including time offset and -especially- E2E (end-to-end) delay to its serving base station 21 1 . Since the E2E delay can be different in the two directions, two measurements can be correspondingly reported to the base station 21 1 (first message Delay (dM->s) and offset report 701 , second message Delay (ds->M) report 702).
  • first message Delay (dM->s) and offset report 701 second message Delay (ds->M) report 702
  • ds->M second message Delay
  • dot-and-dash line arrows 501 , 502, 503, 504, 505, 506 and dashed line arrow 507 show the PTP signaling
  • solid line arrows 701 , 702, 703 indicate the new disclosed signaling between UE 201 and the base station 21 1 .
  • the base station 21 1 is normally aware -or can measure- the access delay to the reporting UE 201 , which depends on parameters including timing advance (TA), delays due to queuing, processing etc. Considering all these, the base station 21 1 calculates the part of the delay corresponding to the path between c-server 232 and base station 21 1 (without access delay). Since this is the common delay part for all UEs 201 attached to this base station 21 1 , it is sufficient that one UE 201 or other node exchanging signals with the base station 21 1 , e.g. relay, road side unit etc. implements the PTP and reports measurements to the base station 21 1 . Of course, when measurements are reported from more than one UEs 201 , the accuracy can be naturally improved.
  • TA timing advance
  • the base station 21 1 provides UE-specific sidelink synchronization instructions 703 to all attached UEs 201. These can have the form of a time offset with respect to a predefined known time reference, e.g. a dressingtime shift" with respect to the UE-specific time reference instructed for UL, as shown in Fig. 8 by reference sign 703. All the synchronization-relevant information exchanged between UE 201 and eNB 21 1 can be e.g. transmitted in the control and feedback channels within the downlink frequency resources.
  • the UE 201 does not update its timing for DL/UL, neither does the base station 21 1.
  • the UE 201 only estimates and tracks the c-server 232 timing, reports to the eNB 21 1 and receives instructions 703 for its own sidelink (SL) timing.
  • SL sidelink
  • the (at least one) UE 201 implements PTP and estimates E2E (C-server 232 to UE 201 ) delay and offsets, which are reported to its eNB 21 1 via UL.
  • the eNB 21 1 calculates the c-server-to-eNB delay, which is common for all UEs 201 attached to the eNB 21 1.
  • UE-specific synchronization instructions 703 are provided to all attached UEs 201.
  • UEs 201 can synchronize their time reference for sidelink.
  • the procedure can be implemented by more than one UE 201 and with a variable frequency.
  • C-server 232 The three main entities shown in Fig. 7, i.e. C-server 232, base station/eNB 211 and mobile user/UE 201 can be implemented as described in the following:
  • the base station 21 1 may be for example an eNodeB or a gNodeB for synchronizing at least one user equipment, e.g. UE 201 , for its uplink 205 and/or sidelink 204
  • the base station 211 comprises a processor which is configured to perform the following: forward at least one time synchronization message 501 , 503, 506 of a time synchronization protocol, in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP, between a time reference server (also denoted as C-server 232 in the figures) and at least one UE (201 ); receive synchronization information 701 of the at least one UE 201 about the synchronization between the at least one UE 201 and the time reference server 232, in particular an end-to-end delay between the time reference server 232 and the at least one UE 201 ; and transmit a synchronization instruction 703 to the at least one UE 201.
  • a time synchronization protocol in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP
  • the base station 21 1 is enabled to acquire synchronization information about the time reference server 232 and/or an end-to-end delay.
  • the base station 211 thus enables the at least one UE 201 synchronizing with the time reference server 232 as shown in Fig. 7.
  • UEs’ 201 uplink and/or sidelink communication can follow a time reference based on the time reference server 232 and are time-aligned/synchronized with each other.
  • the BS 21 1 does not need to synchronize with the time reference server 232 as well, but this can be an optional feature.
  • the time reference finally used by the UEs 201 , 202, 203 does not need to be the server reference, but is based/depending on it.
  • the processor can use a second time reference, which is not based on a time reference of the time reference server 232, for synchronization of downlink communication with the at least one UE 201.
  • the BS 211 may be configured to use a time reference of the time reference server 232 for synchronizing of downlink communication with the at least one UE 201.
  • the synchronization information 701 in particular the end-to-end delay, between the time reference server 232 and the at least one UE 201 may be based on a delay from the time reference server 232 to the at least one UE 201 and/or a delay from the at least one UE 201 to the time reference server 232.
  • the term“based on” can be in particular an average, e.g. a weighted average, between delays in different directions and/or from more than one UEs.
  • the processor can determine an access delay between the base station 21 1 and the at least one UE 201.
  • the processor may be configured to determine the access delay between the base station 211 and the at least one UE 201 based on UE-specific information provided by the at least one UE 201 , in particular depending on radio propagation delay, known contribution of the base station 211 to the access delay and timing advance, TA.
  • the processor can determine a network delay between the time reference server 232 and the base station 21 1 based on the synchronization information 701 , in particular the end- to-end delay, and the access delay.
  • the base station 21 1 may be configured to use the network delay for synchronization of the at least one UE 201.
  • the processor can determine the time reference of the time reference server based on the network delay.
  • the processor can transmit synchronization instructions 703 to a plurality of UEs.
  • the synchronization instructions 703 can be UE-specific, for example, or specific to a group of UEs.
  • the synchronization instructions 703 may be based on the network delay and UE-specific time measurements and parameters, in particular radio propagation delay and known contribution of the base station 211 to the access delay and UE-specific timing advance, TA.
  • the processor can forward the at least one time synchronization message 501 , 503, 506 between the time reference server 232 and the at least one UE 201 without participating in the time synchronization protocol.“Without participating in the time synchronization protocol” in the sense of the invention comprises that the BS does not implement the synchronization protocol itself and takes a role within the communication according to this protocol, and/or that the BS does not read the time synchronization message.
  • the processor can be configured to prioritize forwarding the at least one time
  • the processor can request the at least one UE 201 providing the synchronization information 701 , in particular the end-to-end delay, between the time reference server 232 and the at least one UE 201. If the BS realizes that the synchronization should be updated it can request so.
  • the synchronization information 701 in particular the end-to-end delay, between the time reference server 232 and the at least one UE 201 can be periodically received from the at least one UE 201.
  • the processor can request the at least one UE 201 changing a period for reporting the synchronization information 701 , in particular the end-to-end delay, in particular if the base station 21 1 detects changes in network delay between the time reference server 232 and the base station 21 1.
  • the user equipment, UE 201 can be used for assisting the base station 21 1 (or another base station) for synchronizing at least one user equipment, UE 201 , e.g. UE 201 or another UE, for its uplink 205 and/or sidelink 204 communication.
  • the UE 201 comprises a processor configured to perform the following: receive a time synchronization message 501 , 503, 506 of a time synchronization protocol, in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP, from a time reference server 232 (e.g.
  • the C- server determines synchronization information 701 about a synchronization between the UE 201 and the time reference server 232, in particular an end-to-end delay between the time reference server 232 and the UE 201 , based on the time synchronization message 501 , 503, 506; report the synchronization information 701 to the base station 21 1 ; and receive a synchronization instruction 703 from the base station 21 1 for synchronizing the UE’s uplink 205 and/or sidelink 204 communication.
  • the processor can be configured to report the synchronization information to the base station via an Uplink feedback channel.
  • the processor can be configured to receive the UE-specific synchronization instructions from the base station via a Downlink control channel.
  • the processor can be configured to align a clock offset with the time reference server based on a first synchronization message received from the time reference server and particularly based on a first follow-up message to the first synchronization message according to the PTP/NTP protocol.
  • the processor can be configured to determine a master-to-slave delay indicating a delay between the time reference server and the UE based on the aligned clock offset and a second synchronization message received from the time reference server and particularly based on a second follow-up message to the second synchronization message according to the PTP/NTP protocol.
  • the processor can be configured to determine a slave-to-master delay indicating a delay between the UE and the time reference server based on a delay response message received from the time reference server and in particular based on a follow-up message to the delay response message according to the PTP/NTP protocol.
  • the first synchronization message, the second synchronization message and the delay response message can be received from the time reference server without modification by the base station message according to the PTP/NTP protocol.
  • the UE 201 may comprise: a first modem 1202 (e.g. as shown in Fig. 12) comprising a first protocol stack 1020, PC5, for processing the UE’s 201 sidelink 204 communication; and a second modem 1201 (e.g. as shown in Fig. 12) comprising a second protocol stack 1010, Uu, for processing Uplink/Downlink 205 communication with the base station 211 , wherein the first protocol stack 1020 and the second protocol stack 1010 comprise a shared IP layer 1001 , a shared Radio Resource Connection, RRC, layer 1002 and separate MAC layers 1005, e.g. as described below with respect to Figures 10 and 11.
  • a first protocol stack 1020 e.g. as shown in Fig. 12
  • a second modem 1201 e.g. as shown in Fig. 12
  • the first protocol stack 1020 and the second protocol stack 1010 comprise a shared IP layer 1001 , a shared Radio Resource Connection, RRC, layer 1002 and separate MAC layers
  • the processor may be configured to process the time synchronization protocol based on the shared IP layer 1001 and to synchronize the UE’s 201 uplink 205 and/or sidelink 204 communication based on the shared RRC layer 1002 or based on the separate MAC layers 1005, e.g. as described below with respect to Figures 10 and 1 1.
  • the processor may be configured to compensate an internal delay between the first modem 1202 and the second modem 1201 and to synchronize the UE 201 with the time reference server 232 based on the compensated internal delay.
  • the processor may be configured to report the synchronization information, in particular the end-to-end delay to the base station 21 1 , wherein the synchronization information includes an internal delay between the first modem 1202 and the second modem 1201 , e.g. as described below with respect to Figure 12.
  • the processor may be configured to provide a synchronization instruction 91 1 , 921 to another UE 203 that is out of coverage from the base station 211 , e.g. as described below with respect to Figure 9.
  • the processor may be configured to provide the synchronization instruction 91 1 , 921 to the other UE 203 via a sidelink 204 control channel between the UE 201 and the other UE.
  • the synchronization information provided to the other UE can be specific for the other UE.
  • the UE 201 can be configured to measure a delay, in particular a round-trip delay, between the UE 201 and the other UE 203 and to base the synchronization instruction 703 on this delay.
  • An overall delay is complemented by the delay between the UE and the other UE.
  • the UE 201 may be configured to receive a request from the other UE 203 to measure the delay.
  • the time reference server 232 can be used for synchronizing at least one user equipment, e.g. UE 201 , for its uplink and/or sidelink communication.
  • the time reference server comprises a processor which is configured to: transmit at least one time synchronization message 501 , 503, 506 of a time synchronization protocol, in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP, to the at least one UE 201.
  • the at least one synchronization message 501 , 503, 506 comprises information to enable the at least one UE 201 to report synchronization information 701 about a synchronization between the at least one UE 201 and the time reference server 232, in particular an end-to-end delay between the time reference server 232 and the at least one UE 201.
  • Such a time reference server 232 provides the advantage that the UE can then be configured to report the synchronization information to a base station to enable the base station transmitting a synchronization instruction to the at least one UE for synchronizing the UE’s uplink and/or sidelink communication.
  • the processor can be configured to transmit a first synchronization message 501 and particularly a first follow-up message 502 to the first synchronization message 501 via bypassing the base station 211 to the UE 201.
  • the processor can be configured to transmit a second synchronization message 503 and particularly a second follow-up message 504 to the second synchronization message 503 via bypassing the base station 211 to the UE 201.
  • the processor can be configured to receive a delay request message 505 via bypassing the base station 21 1 from the UE 201.
  • the processor can be configured to transmit a delay response message 506 and particularly a follow-up message 507 to the delay response message 506 via bypassing the base station 211 to the UE 201.
  • the time reference server 232 can be configured to transmit the time synchronization message to a plurality of operator networks; and/or to be operated extern of an operator network. This provides the advantage that the time reference server can be used operator-independent.
  • Fig. 8 shows a message sequence chart 800 illustrating the principle of transparent clock according to the disclosure. If base stations should serve as bridges, the PTP would have to be implemented by all base stations and all attached UEs. This would result into a large signaling overhead compared to the disclosed solution.
  • a master 801 that may represent the C-server 232 described above exchanges synchronization messages 501 , 502, 505, 506 according to a PTP protocol with a bridge 802, e.g. a base station 211 as described above. Then, the bridge 802, e.g. the base station 21 1 exchanges synchronization messages 501 , 502 according to a PTP protocol with a slave 803, e.g. a UE 201 as described above.
  • the master 801 can determine delay measurement 811 (only in P2P bridges) and the slave 803 can determine delay d and residence time t3-t2, where t 2 is the arrival time of synch message 501 at the bridge 802 and t 3 is arrival time of the delay response message 506 at the bridge 802.
  • the base stations 21 1 , 221 are more actively involved in the synchronization procedure, e.g. by applying the PTP and serving as “transparent clock” for all attached UEs 201 , 202, which would also apply the PTP.
  • delays between c-server 232 and base station 21 1 , 221 as well as“residence times” would be“invisible” to the UEs 201 , 202 as UEs 201 , 202 would see only the time stamps, i.e. time reference defined by the bridge 802.
  • Fig. 8 the basic principle of“transparent clocks” or“bridges” 802 is shown in Fig. 8.
  • the main drawback is that all UEs and base stations would have to implement the PTP, resulting in a large signaling overhead between c-server, base stations and mobile users.
  • Fig. 9 shows a message sequence chart 900 illustrating synchronization of UEs without cellular coverage according to the disclosure.
  • In-coverage UEs 201 act as“transparent clocks”, allowing other UEs 203 to synchronize by implementing the PTP, without being aware of the delays and offsets of the C-server-to-UE path.
  • In-coverage UE 201 provides direct synchronization information through a sidelink control channel.
  • Including out-of-coverage UEs e.g. UE 203 shown in Fig. 9, is an essential component in the considered communication scenario.
  • two possible solutions are hereby disclosed and shown in Fig. 9.
  • the first option 910 requires that in-coverage UEs 201 act as“transparent clocks” (firstly defined in IEEE 1588-2008), allowing attached out-of-coverage UEs 203 to synchronize by implementing the PTP.
  • This architecture has the positive aspect that the attached UE 203 does not need to be aware or consider in any way the delays and offsets behind the in-coverage UE 201 , i.e. from C-server-to-UE path. Of course, this requires that all out-of- coverage UEs 203 indeed run the PTP.
  • the second option 920 goes into the direction of the in-coverage UE 201 taking over a role similar as the eNB 21 1. It provides directly synchronization information through a sidelink control channel to the out-of-coverage UE 203, including synchronization information 921 , 922, 923 similar to the one the eNB 21 1 would have provided.
  • a delay measurement can be included, in order to compensate differences in the access delay between different pairs or groups of UEs.
  • synchronization and follow-up messages 91 1 are transmitted from in-coverage UE 201 to out-of-coverage UE 203.
  • Out-of-coverage UE 203 answers with delay request (t R ) message 912 and in-coverage UE 201 transmits delay response (t R ) to out-of-coverage UE 203.
  • synchronization message 921 is transmitted from in-coverage UE 201 to out-of-coverage UE 203.
  • the synchronization message 921 includes timing offset Toff as a function of At, t 0ff and timing advance TA.
  • Out-of-coverage UE 203 answers with delay request (t R ) message 922 and in-coverage UE 201 transmits delay response (t R )/T 0ff update message 923 to out-of-coverage UE 203.
  • Figs. 10 and 11 show a schematic diagrams illustrating an exemplary implementation of protocol stacks 1000, 1 100 in a mobile (vehicular) network including C-server, base station/eNB and UE according to a first and a second implementation form.
  • the c-server 232 includes an RRC/MAC controller and an IP layer;
  • the eNB includes a physical (PHY) layer 1006, a MAC layer 1005, an RLC layer 1004, a PDCP layer 1003 and an RRC layer 1002;
  • the UE 201 includes a protocol stack 1010 implementing the uplink/downlink communication link Uu and a protocol stack 1020 implementing the sidelink communication PC5.
  • the uplink/downlink stack 1010 includes a physical (PHY) layer 1006, a MAC layer 1005, an RLC layer 1004, a PDCP layer 1003, a common RRC layer 1002 (common with the sidelink stack 1020) and a common IP layer 1001 (common with the sidelink stack 1020).
  • the sidelink stack 1020 includes a physical (PHY) layer 1006, a MAC layer 1005, an RLC layer 1004, a PDCP layer 1003, a common RRC layer 1002 (common with the uplink/downlink stack 1010) and a common IP layer 1001 (common with the uplink/downlink stack 1010).
  • PHY physical
  • MAC media access control
  • RLC Radio Link Control
  • PDCP packet data convergence protocol
  • IP common IP layer
  • arrows 101 1 (in Fig. 10) and 1 11 1 (in Fig. 11 ) indicate the PTP flow
  • arrows 1012, 1013 (in Fig. 10) and 11 12, 1 113, 1 114 (in Fig. 1 1 ) indicate the new signaling required for sidelink synchronization.
  • the UE 201 has the capability of connecting to both UL/DL and SL, it will include two protocol stacks 1010, 1020, which may, however, share the upper Radio Resource Connection (RRC) 1002 and IP 1001 layers.
  • RRC Radio Resource Connection
  • the PTP between UE 201 and C-server 232 has to be implemented on IP 1001 , in the general case where the C-server 232 is outside the MNO’s network.
  • the C- server 232 is inside the MNO’s network, it can be also implemented on PDCP 1003.
  • synchronization information 1013 in Fig.
  • Fig. 12 shows a schematic diagram illustrating an exemplary implementation of clock distribution within the UE according to the disclosure. Clock distribution within the UE 201 may introduce delays. The communication interface used for delay measurements needs to be carefully chosen. Internal delays can be either considered as part of the overall E2E delay or compensated internally by each UE separately.
  • the UE 201 includes a first component, e.g. a first modem 1201 to perform DL/UL communication and a second component, e.g. a second modem 1202 to perform sidelink communication.
  • Internal clock distribution 1203 between the first modem 1201 and the second modem 1202 can result in different clock references.
  • a further implementation-related aspect on the UE side is the definition of the connection and measurement interface.
  • clock distribution within the UE 201 e.g. between the UL/DL 1201 and SL 1202 units or modems, will introduce a delay.
  • the DL/UL unit 1201 performs all measurements with c-server232 and receives instructions. Internally, instructions provided by eNB 21 1 need to be adjusted considering the measured/known internal delays before used for the SL unit 1202.
  • E2E delay is defined between c-server 232 and UE SL unit 1202. This means that the PTP is implemented on the SL unit 1202 and measurements/instructions are relayed over the DL/UL unit 1201 to the eNB 21 1.
  • Fig. 13 shows a schematic diagram illustrating a method 1300 for synchronizing a UE 201 for its uplink and/or sidelink communication, from base station 211 side, according to the disclosure.
  • the method 1300 includes forwarding 1301 at least one time synchronization message 501 , 503, 506, e.g. as described above with respect to Fig. 5, of a time synchronization protocol, in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP, between a time reference server 232 and at least one UE 201 , e.g. as described above with respect to Figs. 6 and 7.
  • the method 1300 further includes receiving 1302 synchronization information 701 of the at least one UE 201 about the synchronization between the at least one UE 201 and the time reference server 232, in particular an end-to-end delay between the time reference server 232 and the at least one UE 201 , e.g. as described above with respect to Figs. 6 and 7.
  • the method 1300 further includes transmitting 1303 a synchronization instruction 703 to the at least one UE 201 , e.g. as described above with respect to Figs. 6 and 7.
  • Fig. 14 shows a schematic diagram illustrating a method 1400 for synchronizing a UE 201 for its uplink and/or sidelink communication, from UE 201 side, according to the disclosure.
  • the method 1400 includes receiving 1401 a time synchronization message 501 , 503, 506, e.g. as described above with respect to Fig. 5, of a time synchronization protocol, in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP, from a time reference server 232, e.g. as described above with respect to Figs. 6 and 7.
  • a time synchronization protocol in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP
  • the method 1400 further includes determining 1402 synchronization information 701 about a synchronization between the UE 201 and the time reference server 232, in particular an end-to-end delay between the time reference server 232 and the UE 201 , based on the time synchronization message 501 , 503, 506, e.g. as described above with respect to Figs. 6 and 7.
  • the method 1400 further includes reporting 1403 the synchronization information 701 to a base station 211 , e.g. as described above with respect to Figs. 6 and 7.
  • the method 1400 further includes receiving 1404 a synchronization instruction 703 from the base station 21 1 for synchronizing the UE’s uplink 205 and/or sidelink 204
  • the present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing steps described herein, in particular the steps of the methods 1300, 1400 and the flowcharts 400a, 400b, 500, 700, 800, 900 described above with respect to Figs. 4-5, 7-9 and 13-14.
  • a computer program product may include a readable non-transitory storage medium storing program code thereon for use by a computer.
  • the program code may perform the processing and computing steps described herein, in particular the methods 1300, 1400 and the flowcharts 400a, 400b, 500, 700, 800, 900 described above with respect to Figs. 4-5, 7-9 and 13-14.

Abstract

L'invention concerne des techniques de synchronisation temporelle à commande réseau pour une communication de liaison latérale et/ou de liaison montante d'UE, en particulier pour une communication de liaison latérale et/ou de liaison montante entre opérateurs. L'invention concerne notamment une station de base, en particulier un eNodeB ou un gNodeB, pour synchroniser au moins un équipement utilisateur (UE) pour sa communication de liaison montante et/ou latérale. La station de base comprend un processeur configuré pour : transmettre au moins un message de synchronisation temporelle d'un protocole de synchronisation temporelle, en particulier un protocole de précision temporelle (PTP) ou un protocole de synchronisation de réseau (NTP) entre un serveur de référence temporelle et au moins un UE; recevoir dudit au moins un UE des informations de synchronisation relatives à la synchronisation entre ledit au moins un UE et le serveur de référence temporelle, en particulier un retard de bout en bout entre le serveur de référence temporelle et ledit au moins un UE; et transmettre une instruction de synchronisation audit au moins un UE. L'invention concerne en outre un UE correspondant et un serveur de référence temporelle correspondant.
PCT/EP2018/059916 2018-04-18 2018-04-18 Techniques de synchronisation temporelle à commande réseau pour une communication de liaison latérale et/ou de liaison montante d'ue WO2019201438A1 (fr)

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CN201880092504.7A CN111989960B (zh) 2018-04-18 针对ue侧行链路和/或上行链路通信的基于网络的时间同步的技术

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US20220345870A1 (en) * 2021-04-22 2022-10-27 Nokia Technologies Oy Adaptive relay discovery
WO2022236560A1 (fr) * 2021-05-10 2022-11-17 浙江吉利控股集团有限公司 Procédé de synchronisation temporelle coopérative d'infrastructure de véhicule, appareil de synchronisation temporelle coopérative d'infrastructure de véhicule, et système
WO2023218900A1 (fr) * 2022-05-13 2023-11-16 キヤノン株式会社 Dispositif de communication, procédé de commande de dispositif de communication et programme

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