CN114727379A

CN114727379A - Synchronization method, synchronization device, storage medium and equipment

Info

Publication number: CN114727379A
Application number: CN202110003944.4A
Authority: CN
Inventors: 张雨虹; 陈腾豪
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-01-04
Filing date: 2021-01-04
Publication date: 2022-07-08

Abstract

The application belongs to the technical field of mobile communication, and particularly discloses a synchronization method, a synchronization device, a storage medium and a device, which comprise: acquiring GNSS signals from global navigation satellite system satellites and generating pulse-per-second (1pps) signals; selecting one synchronization mode from a plurality of synchronization modes as a synchronization mode of the first user equipment at least partially according to the GNSS signal and the 1pps signal, and synchronizing the first user equipment with a synchronization reference source corresponding to the synchronization mode of the first user equipment, wherein the plurality of synchronization modes comprise a satellite synchronization mode with the GNSS as the synchronization reference source and a reference UE synchronization mode with a second user equipment as the synchronization reference source. By improving the stability of synchronization, the packet receiving rate of synchronous communication is further improved.

Description

Synchronization method, synchronization device, storage medium and equipment

Technical Field

The present application relates to the field of mobile communications technologies, and in particular, to a synchronization method, an apparatus, a storage medium, and a device.

Background

In various application scenarios of wireless communication (e.g., V2V (Vehicle to Vehicle), V2I (Vehicle to Infrastructure), and V2P (Vehicle to human) in LTE-V2X (Long Term Evolution to Evolution, Vehicle-mounted unit based on 4G LTE system communicates with other devices)), in order to maintain the correctness of communication, User Equipments (UEs) in the same system need to follow the same timing, i.e., synchronous timing.

In the application scenario of LTE-V2X, the OBUs (On-Board units) and the Road-Side units (Road-Side units) may communicate with each other through a PC5(ProSe Direct Communication) interface, in addition to satellite Communication. The PC5 interface is a direct communication interface that exchanges data directly between user devices without forwarding through a base station, and is one of interfaces for D2D (Device to Device) direct communication. For a UE, synchronization with a synchronization reference source corresponding to a synchronization mode selected from a plurality of synchronization modes, wherein the plurality of synchronization modes includes a satellite synchronization mode using a GNSS satellite as a synchronization reference source.

In the prior art, the UE determines whether to select the satellite synchronization mode according to whether the received satellite signal is reliable, that is, if the satellite signal is reliable, the satellite synchronization mode is selected, otherwise, other synchronization modes are selected. However, when performing satellite synchronization with a GNSS satellite as a synchronization reference source, the UE needs to simultaneously refer to the satellite signal and a pulse per second (1pps) signal generated by the UE. That is, if the generated 1pps signal is unstable, the effect of synchronizing the UE with the satellite, i.e., the accuracy of communication between the UE and the satellite, is also affected.

Disclosure of Invention

In order to solve the above-mentioned drawbacks and further improve the communication accuracy between the UE and the satellite, according to some embodiments of the present application, a synchronization method, an apparatus, a storage medium, and a device are provided.

According to some embodiments of the present application, there is first provided a synchronization method for a first user equipment, comprising: acquiring a Global Navigation Satellite System (GNSS) signal from a GNSS Satellite and generating a pulse per second (1pps) signal; selecting one synchronization mode from a plurality of synchronization modes as a synchronization mode of the first user equipment at least partially according to the GNSS signal and the 1pps signal, and synchronizing the first user equipment with a synchronization reference source corresponding to the synchronization mode of the first user equipment, wherein the plurality of synchronization modes comprise a satellite synchronization mode with the GNSS as the synchronization reference source and a reference UE synchronization mode with a second user equipment as the synchronization reference source.

In the synchronization method, the plurality of synchronization modes further includes a self-synchronization mode using the first user equipment as the synchronization reference source.

In the synchronization method, the selecting one synchronization mode from a plurality of synchronization modes as the synchronization mode of the first user equipment at least partially according to the GNSS signal and the 1pps signal includes: selecting the satellite synchronization mode as the synchronization mode of the first user equipment when the number of the GNSS satellites is equal to or greater than a first threshold value, a Reference Signal Power Level (Reference Signal Power Level) of the GNSS satellites is equal to or greater than a second threshold value, and a period of the 1pps Signal is 1s or the period is within a set range.

In the synchronization method, the selecting one synchronization mode from a plurality of synchronization modes as the synchronization mode of the first user equipment at least partially according to the GNSS signal and the 1pps signal includes: determining whether a Sidelink Reference Signal received Power (S-RSRP) from the second user equipment is greater than or equal to a third threshold in at least one of the following cases; wherein the following cases include: the number of the GNSS satellites is smaller than a first threshold, the Reference Signal Power Level (Reference Signal Power Level) of the GNSS satellites is smaller than a second threshold, and the period of the 1pps Signal is not 1s or is not in a set range; selecting the reference UE synchronization pattern as the synchronization pattern of the first user equipment if it is determined that the reference signal received power from the second user equipment is greater than or equal to the third threshold.

In the above synchronization method, the set range of the period of the 1pps signal is 1s ± 100 ns.

In the synchronization method, the selecting one synchronization mode from a plurality of synchronization modes as the synchronization mode of the first user equipment at least partially according to the GNSS signal and the 1pps signal includes: selecting the self-synchronization mode as the synchronization mode of the first user equipment if it is determined that the reference signal received power from the second user equipment is less than the third threshold.

Compared with the prior art, the synchronization method monitors the synchronization condition by combining with the 1pps signal, and timely switches the synchronization mode of the first user equipment according to the synchronization condition, so that the packet receiving rate of the first user equipment is improved.

There is also provided, in accordance with some embodiments of the present application, an in-vehicle unit for a first user equipment, comprising: a Global Navigation Satellite System (GNSS) unit for acquiring a GNSS signal from the GNSS and generating a 1pps signal; a modulation and demodulation unit, configured to select one synchronization mode from multiple synchronization modes as a synchronization mode of the first user equipment at least partially according to the GNSS signal and the 1pps signal, and synchronize the first user equipment with a synchronization reference source corresponding to the selected one synchronization mode, where the multiple synchronization modes include a satellite synchronization mode in which the GNSS is used as the synchronization reference source and a reference UE synchronization mode in which a second user equipment is used as the synchronization reference source.

In the above vehicle-mounted unit, the plurality of synchronization modes further include a self-synchronization mode using the first user equipment as the synchronization reference source.

In the above vehicle-mounted unit, the selecting one synchronization mode from a plurality of synchronization modes as the synchronization mode of the first user equipment based at least in part on the GNSS signal and the 1pps signal comprises: selecting the satellite synchronization mode as the synchronization mode of the first user equipment when the number of the GNSS satellites is equal to or greater than a first threshold value, a Reference Signal Power Level (Reference Signal Power Level) of the GNSS satellites is equal to or greater than a second threshold value, and a period of the 1pps Signal is within a set range.

In the above vehicle-mounted unit, the selecting one synchronization mode from a plurality of synchronization modes as the synchronization mode of the first user equipment at least partially according to the GNSS signal and the 1pps signal includes: determining whether a Sidelink Reference Signal received Power (S-RSRP) from the second user equipment is greater than or equal to a third threshold in at least one of the following cases; wherein the following cases include: the number of the GNSS satellites is smaller than a first threshold, the Reference Signal Power Level (Reference Signal Power Level) of the GNSS satellites is smaller than a second threshold, and the period of the 1pps Signal is not in a set range; selecting the reference UE synchronization pattern as the synchronization pattern of the first user equipment if it is determined that the reference signal received power from the second user equipment is greater than or equal to the third threshold.

In the above-described on-board unit, the set range of the period of the 1pps signal is 1s ± 100 ns.

In the above vehicle-mounted unit, the selecting one synchronization mode from a plurality of synchronization modes as the synchronization mode of the first user equipment based at least in part on the GNSS signal and the 1pps signal comprises: selecting the self-synchronization mode as the synchronization mode of the first user equipment if it is determined that the reference signal received power from the second user equipment is less than the third threshold.

Compared with the prior art, the modulation and demodulation unit in the vehicle-mounted unit for the first user equipment judges the stability of the 1pps signal of the physical layer, and determines the synchronization mode of the first user equipment by combining the judgment result, so that the packet receiving rate of the first user equipment is further improved.

According to some embodiments of the present application, there is also provided a computer-readable storage medium for storing computer instructions which, when executed, implement the above-described method.

According to some embodiments of the present application, there is also provided a first user equipment comprising: a processor; a memory for storing computer instructions which, when executed by the processor, may cause the first user equipment to perform the above-described method.

Compared with the prior art, the GNSS signal, the 1pps signal and the signal from the reference UE are comprehensively considered in the synchronous switching process of the first user equipment, so that the defect that the first user equipment continues to select the satellite synchronization mode only according to reliable judgment of the GNSS signal when the 1pps signal is unstable in the prior art is overcome, and the packet receiving rate of the first user equipment is further improved.

Drawings

FIG. 1 is a schematic view of a vehicle networking system, according to some embodiments of the present application;

FIG. 2 is a diagram illustrating switching of a UE in different synchronization modes according to the prior art;

FIG. 3 is a schematic diagram of an On-Board Unit (OBU) according to some embodiments of the present application;

fig. 4 is a schematic diagram of a user equipment switching in different synchronization modes according to some embodiments of the present application;

FIG. 5 is a flow diagram of a synchronization method performed by an OBU, according to some embodiments of the present application;

fig. 6 illustrates a system diagram of a user device provided in accordance with some embodiments of the present application.

Detailed Description

The following description of the embodiments of the present application is provided by way of specific examples, and other advantages and effects of the present application will be readily apparent to those skilled in the art from the disclosure herein. While the description of the present application will be presented in conjunction with the preferred embodiments, it is not intended to limit the features of the present invention to that embodiment. Rather, the invention has been described in connection with embodiments for the purpose of covering alternatives and modifications as may be extended based on the claims of the present application. In the following description, numerous specific details are included to provide a thorough understanding of the present application. The present application may be practiced without these particulars. Moreover, some of the specific details have been omitted from the description in order to avoid obscuring or obscuring the focus of the present application. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

Further, various operations will be described as multiple discrete operations, in a manner that is most helpful in understanding the illustrative embodiments; however, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation. It should be noted that in this specification, like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings.

It will be understood that, although the terms "first", "second", etc. may be used herein to describe various features, these features should not be limited by these terms. These terms are used merely for distinguishing and are not intended to indicate or imply relative importance. For example, a first feature may be termed a second feature, and, similarly, a second feature may be termed a first feature, without departing from the scope of example embodiments.

The terms "comprising," "having," and "including" are synonymous, unless the context dictates otherwise. The phrase "A/B" means "A or B". The phrase "A and/or B" means "(A), (B) or (A and B)".

As used herein, the terms "module," "unit," "device" may refer to or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality, or may be part of an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

It should be noted that, in the present application, the numbering of the method and the flow is for convenience of reference, but not for limitation of the sequence, and if there is a sequence between the steps, the text is used as the standard.

To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of a vehicle networking system 100 provided in accordance with some embodiments of the present application. The car networking System 100 includes a User Equipment (UE) 101 and a GNSS (Global Navigation Satellite System) Satellite 102. The UE101 may be an Internet of things device, such as a Road-Side Unit (RSU) 101a and a plurality of vehicles (e.g., UEs 101b, c). The RSU101a is generally a public facility fixed at the Road Side, and can maintain stable and reliable communication with the GNSS satellite 102 in many cases, and can provide synchronization Information and Information about Road control Information such as MAP (MAP) Information, Signal Phase and Timing Message (SPAT), Road Side unit Message (RSI), and Road Side safety Message (RSM) to other UEs, for example, UEs 101b and c, as a synchronization reference source. The UE101b or UE101c may include, but is not limited to, a vehicle mounted power supply power, a V2X/GNSS antenna, an On-Board Unit (OBU), and various buses such as a CAN bus. Among other things, the OBU in the UE101 may communicate with the GNSS satellite 102 directly via the V2X/GNSS antenna to obtain GNSS satellite signals, and may also communicate with other UEs (e.g., between the UE101 b/UE101c and the RSU101a, or between the UE101b and the UE101c) to obtain synchronous reference signals. Typically, the synchronization reference signal is acquired from a PSB (Physical Sidelink Broadcast) message. To enable the transfer of safety information between vehicles, the OBU unit in UE101 b/UE101c also sends vehicle safety messages (BSMs) without interruption. The GNSS satellites 102 include satellites in any Global Navigation Satellite System (GNSS). Currently, GNSS includes Global Positioning System (GPS), GLONASS (GLONASS) satellite navigation System, GALILEO (GALILEO) satellite navigation System, and BeiDou satellite navigation System (BDS). The UE101 may select one or more of the navigation/positioning systems to synchronize and communicate.

In the car networking system 100 shown in fig. 1, on one hand, since the UE101 (vehicle) is in a high-speed driving state, its own absolute position data keeps constantly updated, and a time factor needs to be considered when calculating the relative distance between two UEs 101, the UEs 101 in the car networking system 100 need to acquire uniform time through the GNSS satellite 102. On the other hand, in the case where there is no GNSS satellite 102 as a reference source for synchronous communication, one UE101 may have another UE101 as a synchronous reference source, and a UE101 that has already synchronized with the GNSS satellite 102 is preferred. In a more extreme case, one UE101 may not search for a reliable GNSS satellite 102 as a synchronization reference source, and may not find another UE101 as a synchronization reference source, so that the UE101 may use itself as a synchronization reference source, but at the same time, search may continue for the GNSS satellite 102 or another UE101 as a synchronization reference source.

Although a system such as the car networking system 100 is shown in fig. 1, it should be understood by those skilled in the art that the present invention can be applied to other suitable wireless communication systems, and the UE101 in fig. 1 can also include other user devices such as mobile phones, tablet computers, notebook computers, palm computers, Mobile Internet Devices (MIDs), wearable devices (including smart watches, smart bracelets, pedometers, etc., for example), personal digital assistants, portable media players, navigation devices, video game devices, set-top boxes, virtual reality and/or augmented reality devices, other internet of things devices, industrial control devices, streaming media client devices, electronic books, reading devices, POS machines, and other devices.

FIG. 2 shows a diagram of UE101 switching between different synchronization modes in the prior art. The different synchronization modes at least include the following three types: satellite sync mode, reference UE sync mode, and self-sync mode. The satellite synchronization mode refers to a synchronization mode in which the UE101 uses the GNSS satellite 102 as a synchronization reference source. In the satellite synchronization mode, the UE101 obtains absolute Time (UTC) information from the GNSS satellite 102 to obtain a synchronous clock for synchronous communication. The reference UE synchronization mode refers to the UE101 using other UEs as synchronization reference sources. Preferably, the other UEs have synchronized with the GNSS satellite 102, e.g., the UE101b has the RSU101a as the synchronization reference source, or the UE101c has the UE101b as the synchronization reference source, etc. In the case where the UE101b has the RSU101a as the synchronization reference source and the UE101c has the UE101b as the synchronization reference source, the UE101b is also referred to as a relay UE. According to some embodiments of the present application, if the S-RSRP value of the synchronization reference source (e.g., RSU101a) in synchronization mode as a reference UE is large enough, then other UEs (e.g., UE101b or UE101c) do not need to be configured as relay UEs or broadcast channels for these other UEs within its coverage area, so as to save system resources and power consumption of the UEs. In the reference UE synchronization mode, the UE101b or UE101c acquires the synchronization signal sent by the other UEs through the PC5 port in their OBUs and uses the synchronization signal as the synchronization clock for synchronizing communications. The self-synchronization mode is that the UE101 performs synchronous communication with itself as a synchronization reference source.

To ensure the requirement of synchronization reliability, in the car networking system 100, the synchronization with the GNSS satellite 102 is the highest priority synchronization mode, followed by the reference UE synchronization mode, and the self-synchronization mode is the lowest priority synchronization mode. For a UE101 at a lower synchronization priority to keep detecting whether a higher priority synchronization mode is available, if a reliable higher priority synchronization reference source is available, the UE101 at the lower synchronization priority needs to switch to the higher priority synchronization mode in time. For example, assuming that a UE101 is in a reference UE synchronization mode, the UE101 needs to keep detecting whether there are reliable GNSS satellites 102, and once there are reliable GNSS satellites 102 present, the synchronization mode of the UE101 can switch to a satellite synchronization mode. For another example, assuming that a UE101 is in a self-synchronization mode, the UE101 needs to keep detecting whether there is a reliable GNSS satellite 102 on one hand, and whether there are other UEs that can be used as synchronization reference sources on the other hand, and if there is a reliable GNSS satellite 102, the UE switches to a satellite synchronization mode, and if there is no reliable GNSS satellite 102 but there are other UEs that are reliable, the UE switches to a reference UE synchronization mode. According to the specifications of table b.6.1-1 in 3GPP36.331, section 5.10.8.2 and in 3GPP36.133, section b.6.1, it can be determined whether GNSS satellites are reliable and whether a switching of synchronization mode is required based on the number of GNSS satellites in the same GNSS system and the Reference Signal Power Level (RSPL) of the received GNSS signals. For example, Table B.6.1-1 specifies that if there are 6 or more satellites in the GPS system and the RSPL from a satellite exceeds-128.5 dBmW, the UE101 can consider a reliable GNSS satellite 102, i.e., the UE101 can select the satellite synchronization mode according to the specification of section 5.10.8.2 of 3GPP 36.331. Similarly, according to Table B.6.1-1, if there are 6 or more satellites in the BDS system and the Reference Signal Power Level (RSPL) from the satellites exceeds-133 dBmW, the UE101 can consider that there are reliable GNSS satellites 102 and the satellite synchronization mode can be selected according to the specification of section 5.10.8.2 of 3GPP 36.331.

Similarly, for a UE101 at a higher synchronization priority, it is also necessary to monitor the synchronization reference source, and when the synchronization reference source becomes unreliable or unstable, it is necessary to switch to a synchronization mode at a lower priority to ensure the reliability of the synchronization communication. For example, assuming that a UE101 is in a satellite synchronization mode, when detecting that the GNSS satellite 102 is unreliable, it is necessary to detect whether other UEs (e.g., RSU101a) in the surroundings are available, and when other UEs are available, the UE101 can switch to a reference UE synchronization mode. If no other UE is available, i.e. no existing reference source can be found, the UE101 switches to the self-synchronization mode. Among them, other UEs in synchronization with the satellite are preferred as synchronization reference sources in the synchronization mode of the reference UE, such as RSU101a (since the road side unit can generally better maintain the state of synchronization with the satellite). According to the above synchronization mode switching method, if a UE101 is in the reference UE synchronization mode, the UE101 needs to keep monitoring whether there is a reliable GNSS satellite 102, and if so, switches to the satellite synchronization mode in time, and on the other hand, when it is detected that other UEs as synchronization reference sources are unavailable, needs to search for the synchronization reference sources again, and switches to the self-synchronization mode in case of no new synchronization reference source. According to the specification of table b.6.2-1 of part b.6.2 of 3GPP36.133, whether other UEs are available can be determined by receiving a Sidelink Reference Signal received Power (S-RSRP) from the other UEs, for example, table b.6.2-1 specifies that the minimum value of S-RSRP is-124 dBmW, and when the S-RSRP value received by the UE101 is equal to or greater than-124 dBmW, the UE101 can determine that the other UEs are available, that is, according to the specification of part 5.10.8.2 of 3GPP36.331, in this case, the UE101 can select the Reference UE synchronization mode.

In the GNSS satellite synchronization mode, where the UE101 synchronizes via a satellite clock, the physical layer (PHY) of the UE101 needs to align the time slots in combination with the GNSS absolute time from the satellite data path (typically from the GNSS chip of the UE101 to the physical layer via the Radio Resource Control (RRC) layer of the UE 101) and the 1pps signal from the GNSS chip. Wherein the 1pps signal is used to compensate for a delay due to the satellite data path. However, in the mode switching process shown in FIG. 2, only the information related to GNSS satellite signals is considered, and the information related to 1pps signals is not considered. The physical layer part specifies the LTE-V2X clock synchronization standard according to the current 3GPP 36.213 protocol, and the RRC (Radio Resource Control) layer part specifies the standard for determining which synchronization mode the UE101 uses in the LTE-V2X system according to the current 3GPP36.331 protocol. That is, the two standards are defined separately, and the standard of the RRC layer does not consider the possible effect of the PHY layer anomaly. However, from the current practical use situation, the 1pps signal has a case where the period is unstable due to a chip problem or a configuration problem. Since the PHY layer is synchronized with reference to the absolute time from the GNSS and the 1pps signal, the work of the PHY layer to synchronize the clock will be affected if the 1pps signal is not stable in period. Specifically, since there is no stable 1pps signal to correct the phase deviation of the crystal oscillator in the UE101, the synchronous clock of the UE101 will gradually generate a phase shift only by the crystal oscillator of the UE101, i.e. the synchronous clock cannot be synchronized with the GNSS satellite 102 or other UEs. However, since the RRC layer does not consider the anomaly of the 1pps signal, if the GNSS satellite 102 is determined to be GNSS-reliable by the RRC layer, the UE101 maintains the GNSS satellite synchronization mode without switching the synchronization mode. However, at this time, if the synchronization clock of the UE101 has shifted, the UE101 cannot normally communicate with other UEs, and the packet reception rate is drastically reduced, which may cause a great safety hazard to vehicles, people, and facilities in the car networking system 100.

FIG. 3 is a schematic diagram of an On-Board Unit (OBU) according to some embodiments of the present application. The GNSS receiver comprises a processing chip GNSS unit 301 for transceiving GNSS signals, a modem unit 302, a radio frequency chip RF IC303, a PC5 interface 304, and other units. The GNSS unit 301 receives information from the GNSS satellites 102, obtains information on GNSS signals, such as the number of GNSS satellites in the same GNSS system, Reference Signal Power Levels (RSPLs) of the GNSS satellites, UTC information, and the like, and outputs the information to the modem unit 302. According to other embodiments, the GNSS unit 301 may also directly output the GNSS signal to the modem unit 302, and the modem unit 302 may analyze and obtain the above information. In addition, the GNSS unit 301 also generates a 1pps signal and outputs the signal to the modem unit 302, or the GNSS unit 301 analyzes the period of the generated 1pps signal and outputs related information to the modem unit 302. The modem unit 302 may determine whether the 1pps signal has instability such as sudden loss, discontinuity, pulse inaccuracy, etc. by determining whether the period of the 1pps signal is one second or not, or whether the period is within a set range (e.g., 1s ± 100ns, where 100ns is a tolerable error of the period). When the period of the 1pps signal is 1 second or within a set range, the 1pps signal is judged to be stable, otherwise, the 1pps signal is judged to be unstable.

The upper layer processing unit 3021 in the modem unit 302 (including the LTEV RRC layer (Long Term Evolution Radio Resource Control)) may determine whether the GNSS satellite is reliable according to the information related to the GNSS signal from the GNSS unit 301 (e.g., whether the number of GNSS satellites in the same system reaches 6 and the RSPL of GNSS signals in different GNSS systems reaches a corresponding minimum value as specified in table b.6.1-1 of part b.6.1 in 3GPP 36.133). At the same time, the GNSS unit 301 generates a 1pps signal, which is also output to a physical layer (LTEV PHY)3022 in the modem unit 302. In other embodiments, the 1pps signal may also be generated by, for example, dividing the local clock. The physical layer 3022 in the modem unit 302 generates a synchronous clock from the 1pps signal from the GNSS unit 301 and the GNSS absolute time from the upper layer processing unit 3021. According to other embodiments of the present application, the LTEV PHY 3022 may also output the 1pps signal itself or information indicating whether the 1pps signal period is stable to the upper layer processing unit 3021 without the GNSS unit 301 providing it to the modem unit 302.

RF IC303 receives Physical Sidelink Broadcast (PSB) messages from other UEs via PC5 interface 304 and down-converts the PSB messages to baseband. According to some embodiments of the present application, the PSB message may include synchronization signals from other UEs and information related to the synchronization signals, for example, subframe boundaries, frame numbers, subframe number information, and the like carried by the PSB message. RF IC303 outputs the downconverted PSB message to LTEV PHY 3022 for the PHY layer to generate a synchronized clock. The physical layer 3022 also outputs information related to the synchronization signal to the upper layer processing unit 3021, so that the RRC layer determines whether the synchronization signal is available (corresponding to determining a reference UE as a synchronization reference source). The information related to the synchronization Signal at least includes a Sidelink Reference Signal Receive Power (S-RSRP).

In the embodiment shown in fig. 3, the information about the 1pps signal is output to the RRC layer (the upper processing unit 3021 in the figure), that is, this embodiment solves the defect in the prior art that the 1pps signal cannot reach the RRC layer, and the RRC layer can comprehensively consider at least three information in the process of deciding how to switch the synchronization mode: whether the GNSS is reliable, whether the 1pps signal is stable, and whether a synchronization signal (REF) of the reference UE is available. Therefore, the defect caused by the fact that 1pps signals do not participate in the judgment of the synchronization mode in the prior art is overcome, normal communication among the UEs 101 in the vehicle networking system 100 is guaranteed, and the safety of vehicles, people and facilities in the vehicle networking system 100 is improved.

Specifically, the process of how to decide according to the three aspects of whether the GNSS is reliable, whether the 1pps signal is stable, and whether the synchronization signal (REF) of the reference UE is available can be seen in fig. 4. Fig. 4 is a schematic diagram of a user equipment switching in different synchronization modes according to some embodiments of the present application.

FIG. 4 shows different scenarios where the UE101 switches in the satellite synchronization mode, the reference UE synchronization mode, and the self-synchronization mode, respectively. The satellite synchronization mode is a mode in which the UE101 performs clock synchronization using the GNSS satellite 102 as a synchronization reference source. The reference UE synchronization mode refers to a mode in which the UE101 performs clock synchronization with another UE synchronization reference source, preferably, the other UE is already synchronized with a satellite. The self-synchronization mode is a mode in which the UE101 performs clock synchronization using itself as a synchronization reference source. The three modes can be switched with each other according to at least the following three conditions: whether the GNSS satellite 102 is reliable, whether the 1pps signal is stable, and whether a synchronization signal (REF) of the reference UE is available.

Whether a GNSS satellite 102 is reliable or not, as specified in Table B.6.1-1 of section B.6.1 of the 3GPP36.133 protocol, may refer to: in the same GNSS system, whether the number of satellites is equal to or greater than a first threshold value, and whether the Reference Signal Power Level (RSPL) of the GNSS signals received by the UE101 from these satellites is equal to or greater than a second threshold value. If the above two conditions are satisfied, the GNSS satellite 102 may be determined to be reliable, otherwise, the GNSS satellite may be determined to be unreliable. Wherein the first threshold and the second threshold are both determined from the above table B.6.1-1. For example, according to table b.6.1-1, in a beidou satellite navigation system (BDS), if the RSPL of at least 6 (first threshold) satellites is greater than-133 dBmW (second threshold), then the GNSS satellite 102 (i.e., beidou satellite) may be determined to be reliable, otherwise the GNSS satellite 102 may be determined to be unreliable. As another example, according to Table B.6.1-1, in a GPS satellite navigation system, a GNSS satellite 102 (i.e., a GPS satellite) may be determined to be reliable if the RSPL of at least 6 (first threshold) satellites is greater than-128.5 dBmW (second threshold), otherwise the GNSS satellite 102 may be determined to be unreliable. In practice, the UE101 may determine the number of GNSS satellites existing in the same system (for example, GPS satellite navigation system or beidou satellite navigation system) according to which satellites the received GNSS signals respectively come from, or if the received GNSS signals carry the number of GNSS satellites existing in the same system, the UE101 may determine the number of GNSS satellites by analyzing the GNSS signals. Alternatively, the GNSS satellites of at least the first threshold (e.g., 6) may be from different GNSS systems, allowing the reception of GNSS signals across GNSS systems (e.g., the GPS satellite navigation system and the beidou satellite navigation system may be used simultaneously). For example, the GNSS information received by the UE101 comes from 3 GPS satellites and 3 beidou satellites, respectively. And the RSPLs from the GPS satellite and the Beidou satellite are respectively larger than the corresponding second threshold values. For example, the RSPL of 3 satellites in the GPS satellite navigation system is greater than-128.5 dBmW (second threshold), and the RSPL of 3 satellites in the Beidou satellite navigation system is greater than-133 dBmW (second threshold).

The 1pps signal is a pulse signal that occurs periodically, for example, 1pps with a period of 1 s. The above-described pulses need to be stable to occur on a periodic basis (e.g., 1s) due to the needs of the communication network. In practice, there is a tolerable error to this period value, e.g., a tolerable maximum error of ± 100 ns. That is, the above-described pulses need to stably occur with a period within 1s ± 100 ns. The UE101 may determine whether 1pps is stable according to various schemes. For example, if the interval time between two adjacent pulses is within a set range (for example, within 1s ± 10 ns), or if the interval time between two adjacent pulses continuously appears n (for example, n < 3) times within the set range (for example, within 1s ± 10 ns), it can be determined that the 1pps signal is stable. If the interval time between two adjacent pulses is not within the set range (for example, within 1s + -10 ns), or if the interval time between two adjacent pulses is continuously present n times (for example, n ≧ 3) times and is not within the set range (for example, within 1s + -10 ns), it can be determined that the 1pps signal is unstable. For another example, when the interval time between two adjacent pulses is not within the set range (e.g., within 1s ± 100 ns) n (e.g., n ≧ 3) times, the interval time between two pulses is not within the set range within a predetermined time (e.g., within 20 s), the 1pps signal is determined to be stable, otherwise, the 1pps signal is determined to be unstable. The scenes in which the interval time is not within the set range may include: firstly, the pulse period is unstable, for example, the pulse lasts for about 1s, but the error of the period is more than +/-100 ns, secondly, the pulse is lost, for example, the interval time between two adjacent pulses is 2s and 3s … …, thirdly, the pulse disappears, for example, after the last pulse appears, the next pulse does not appear for more than m (for example, m is more than or equal to 3) seconds.

As shown in fig. 4, for the Reference UE synchronization mode, according to the specification of table b.6.2-1 in section b.6.2 of 3GPP36.133, whether a synchronization Signal (REF) from the Reference UE is available refers to whether the value of the Sidelink Reference Signal received Power (S-RSRP) from other UEs (i.e., synchronization Reference source in the Reference UE synchronization mode) received by the UE101 is greater than or equal to a third threshold (e.g., -124 mw dbsp), and if S-RSRP is greater than or equal to the third threshold, REF is considered available, otherwise REF is considered unavailable.

Based on the above definitions of whether the GNSS satellite 102 is reliable, whether the 1pps signal is stable, and whether REF is available, the UE101 may monitor and determine the above three conditions to determine whether to continue to maintain the current mode or to switch to another synchronization mode, as shown in FIG. 4. Specifically, in the case where the UE101 determines that the GNSS satellite 102 is unreliable or that the 1pps signal is unstable, and REF is available, the reference UE synchronization mode is selected; selecting a satellite synchronization mode when the UE101 determines that the GNSS satellite 102 is reliable and the 1pps signal is stable; in the case where the UE101 determines that the GNSS satellite 102 is not reliable or that the 1pps signal is not stable, and REF is unavailable, the self-synchronization mode is selected.

In addition, the UE101 may receive PSB messages from other UEs through the PC5 interface 304, wherein the PSB messages contain a synchronization signal (REF) for referencing the UE synchronization mode. In this process, the UE101 may find that a synchronization signal carried in PSB messages sent by a plurality of other UEs may be determined to be available as REF, where other UEs in satellite-synchronous communication may be included, such as other UEs 101 in satellite-synchronous mode (direct communication with satellite-synchronous), or other UEs 101 in satellite-synchronous mode (indirect communication with satellite-synchronous) while in the reference UE-synchronous mode; other UEs 101 that are in a reference UE synchronization mode and the synchronization reference source is not synchronized to the satellite (not communicating synchronously with the satellite) may also be included; or other UEs in self-synchronization mode (not communicating synchronously with the satellite). The UE101 selects one of the plurality of available other UEs as a synchronization reference source in the reference UE synchronization mode. According to the specification of section 5.10.8.2 of 3GPP36.331, the selection order described above may be: preferably, other UEs directly or indirectly synchronized with the satellite are used as the synchronization reference source in the synchronization mode of the reference UE, other UEs not synchronized with the satellite are selected as the synchronization reference source in the synchronization mode of the reference UE, and finally, other UEs in the self-synchronization mode are selected as the synchronization reference source in the synchronization mode of the reference UE.

Also according to the specification of section 5.10.8.2 of 3GPP36.331, if one other UE has been selected as the synchronization reference source in the synchronization mode of the reference UE, and if there are several other UEs to be selected, then the more suitable other UEs can be selected as the synchronization reference source in the synchronization mode of the reference UE according to the following conditions: the S-RSRP of the strongest other UE to be selected exceeds the minimum requirement indicated by the parameter syncRefMinHyst in TS 36.133[16], the strongest other UE to be selected and the current other UE as the synchronous reference source in the synchronization mode of the reference UE belong to the same priority, and the S-RSRP of the strongest other UE to be selected exceeds the S-RSRP of the current other UE as the synchronous reference source in the synchronization mode of the reference UE according to the indication of the parameter syncRefDiffHyst.

In the process of switching the synchronization mode shown in fig. 4, information about whether a 1pps signal generated by the GNSS chip is stable, whether a GNSS satellite is reliable, and whether a synchronization signal REF from other UEs is available is comprehensively considered, so that the defects of the prior art are overcome, more accurate judgment of whether the user equipment is in a good synchronization communication state is facilitated, and the accuracy of packet receiving and sending of the user equipment is facilitated to be improved.

FIG. 5 is a flow chart of a synchronization method performed by the UE101 according to some embodiments of the present application. According to some embodiments of the present application, the method may be performed by an OBU in the UE101, such as the OBU in FIG. 3. As shown in FIG. 5, in step S1, the GNSS chip 301 in the UE101 acquires GNSS signals from GNSS satellites 102, wherein the GNSS satellites 102 may comprise GPS satellites, BDS satellites, or satellites of other GNSS systems. In step S1, the GNSS chip 301 further generates a 1pps signal according to the GNSS signal to assist the physical layer 3022 in the modem unit 302 of the UE101 in time slot alignment of the absolute time of the satellite carried by the GNSS signal.

In step S2, based on the GNSS signal, the RRC layer 3021 in the modem unit 302 in the UE101 determines whether the GNSS signal is reliable. Whether the GNSS satellite 102 is reliable or not, as specified in Table B.6.1-1 of section B.6.1 of the 3GPP36.133 protocol, refers to: in the same GNSS system, whether the number of satellites is equal to or greater than a first threshold value, and whether the Reference Signal Power Level (RSPL) of the GNSS signals received by the UE101 from these satellites is equal to or greater than a second threshold value. If the above two conditions are satisfied, the GNSS satellite 102 may be determined to be reliable, otherwise, the GNSS satellite may be determined to be unreliable. For example, according to the specification of table b.6.1-1 of part b.6.1 of the 3GPP36.133 protocol, when the RRC layer 3021 determines that the RSPL of at least 6 (the first threshold) satellites in the beidou satellite navigation system (BDS) is greater than-133 dBmW (the second threshold) through GNSS signals, the GNSS satellite 102 is determined to be reliable (i.e., the GNSS in fig. 3 is reliable), otherwise the GNSS satellite 102 is determined to be unreliable (i.e., the GNSS in fig. 3 is unreliable).

In step S3, the physical layer 3022 determines whether the 1pps signal is stable. As mentioned above, the 1pps signal is generated by the GNSS chip 301. This is a pulse signal that occurs periodically, and in order to ensure the stability of the synchronous clock of the communication network, the above-mentioned pulse needs to occur stably in cycles (for example, 1 s). In practice, there is a tolerable error to this period value, e.g., a tolerable maximum error of ± 100 ns. That is, the above-described pulses need to stably occur with a period within 1s ± 100 ns. The UE101 may determine whether 1pps is stable according to various schemes. For example, if the interval time between two adjacent pulses is within a set range (for example, within 1s ± 10 ns), or if the interval time between two adjacent pulses continuously appears n (for example, n < 3) times within the set range (for example, within 1s ± 10 ns), it can be determined that the 1pps signal is stable. If the interval time between two adjacent pulses is not within the set range (for example, within 1s + -10 ns), or if the interval time between two adjacent pulses is continuously present n times (for example, n ≧ 3) times and is not within the set range (for example, within 1s + -10 ns), it can be determined that the 1pps signal is unstable. For another example, when the interval time between two adjacent pulses is not within the set range (e.g., within 1s ± 100 ns) n (e.g., n ≧ 3) times, the interval time between two pulses is not within the set range within a predetermined time (e.g., within 20 s), the 1pps signal is determined to be stable, otherwise, the 1pps signal is determined to be unstable.

Alternatively, the physical layer 3022 may output the 1pps signal to the RRC layer 3021 directly, and the RRC layer 3021 may perform the above determination to determine whether the 1pps signal is stable. If the GNSS signal is determined to be reliable and the 1pps signal is stable, the step S3 selects the satellite synchronization mode (step S4), otherwise, the step S5 is performed to acquire the synchronization reference signal transmitted by another UE 101.

In step S4, after entering the satellite synchronization mode, the physical layer 3022 performs the time slot alignment according to the 1pps signal and the UTC information carried by the GNSS signal, so that the UE101 and the GNSS satellite maintain good synchronous communication. On the other hand, the modem unit 302 further returns to step S2 to continuously monitor whether the GNSS signal is reliable, whether the 1pps signal is stable, and whether the REF signal is available, so as to maintain the reliability of the synchronous communication.

In step S5, based on the fact that it has been previously determined that the GNSS signal is not reliable or the 1pps signal is not stable, the RF IC303 receives a PSB (Physical Sidelink Broadcast) message transmitted by another UE through the PC5 interface 304, and the Physical layer 3022 can obtain a synchronization signal (REF) and a value of S-RSRP of the REF therefrom. According to the provisions of table b.6.2-1 of section b.6.2 of 3GPP36.133, whether REF from the reference UE is available means whether the value of S-RSRP received by the UE101 from other UEs (i.e., the reference UE synchronization reference source) is greater than or equal to a third threshold (e.g., -124dBmW), REF is considered available if S-RSRP is greater than or equal to the third threshold, and REF is considered unavailable otherwise.

Typically, the UE101 can receive multiple PSB messages, i.e., the physical layer 3022 can obtain multiple REFs and S-RSRPs of the REFs. In step S6, the RRC layer 3021 determines S-RSRPs of the plurality of REFs according to the above description, and selects another UE whose S-RSRP is greater than or equal to the third threshold. The selected other UEs are considered REF available. But there may be more than one other UE, which may include other UEs in synchronous communication with the satellite, such as other UEs 101 in satellite synchronous mode (communicating directly with the satellite), or other UEs 101 in synchronous communication with the satellite while in reference UE synchronous mode (communicating indirectly with the satellite); other UEs 101 that are in a reference UE synchronization mode and the synchronization reference source is not synchronized to the satellite (not communicating synchronously with the satellite) may also be included; or other UEs in self-synchronization mode (not communicating synchronously with the satellite). In this case, according to the provisions of 3GPP36.331, section 5.10.8.2, the UE101 selection synchronization reference source order may be: preferably, other UEs in direct or indirect synchronous communication with the satellite are used as the synchronous reference source in the synchronous mode of the reference UE, other UEs not in synchronous communication with the satellite are selected as the synchronous reference source in the synchronous mode of the reference UE, and finally, other UEs in the self-synchronous mode are selected as the synchronous reference source in the synchronous mode of the reference UE. In the case where multiple other available UEs are in the same synchronization mode, the UE101 may select the UE with the highest S-RSRP value as the synchronization reference source in the synchronization mode of the reference UE.

After the synchronization reference source is determined, step S7 is performed. Similar to step S4, in step S7, the physical layer 3022 keeps the UE101 in good synchronous communication with the selected synchronous reference source with REF as the synchronous clock. On the other hand, the modem unit 302 further returns to step S2 to continuously monitor whether the GNSS signal is reliable, whether the 1pps signal is stable, and whether the REF signal is available, so as to maintain the reliability of the synchronous communication.

If no suitable synchronization reference source is found after step S6, for example, when no GNSS satellite signal can be received in the tunnel, and no other UE exists, the UE101 uses itself as the synchronization reference source and sends the PSB message through the PC5 interface 304, i.e., enters the self-synchronization mode (step S8). On the other hand, the modem unit 302 returns to step S2 to continuously monitor whether the GNSS signal is reliable, whether the 1pps signal is stable, and whether the REF signal is available, and based on the 3 signals, when the modem unit 302 determines that the satellite synchronization mode or the reference UE synchronization mode is selectable, the UE101 switches to the corresponding mode. That is, when the UE101 is in self-synchronization mode, it is preferable to switch to satellite synchronization mode or reference UE synchronization mode rather than maintaining self-synchronization mode.

In the process of the synchronization method shown in fig. 5, the synchronization state of the user equipment is ensured by continuously and circularly monitoring three information, i.e., whether GNSS is reliable or not, whether 1pps is stable or not, and whether REF is reliable or not, so that "pseudo-synchronization" caused by no consideration of 1pps signals in the prior art is compensated, and the accuracy of receiving and transmitting packets of the user equipment in the car networking system 100 is improved.

FIG. 6 illustrates a system diagram of a user equipment UE101 provided in accordance with some embodiments of the present application.

The UE101 may include a processor 1000, an external memory interface 120, an internal memory 121, a Universal Serial Bus (USB) connector 130, a charging management module 140, a power management module 141, a battery 142, an antenna 1, an antenna 2, a mobile communication module 150, a wireless communication module 160, an audio module 170, a speaker 170A, a receiver 170B, a microphone 170C, an earphone interface 170D, a sensor module 180, a button 190, a motor 191, an indicator 192, a camera 193, a display screen 194, a Subscriber Identification Module (SIM) card interface 195, and the like. The sensor module 180 may include a pressure sensor 180A, a gyroscope sensor 180B, an air pressure sensor 180C, a magnetic sensor 180D, an acceleration sensor 180E, a distance sensor 180F, a proximity light sensor 180G, a fingerprint sensor 180H, a temperature sensor 180J, a touch sensor 180K, an ambient light sensor 180L, a bone conduction sensor 180M, and the like.

It is to be understood that the illustrated structure of the embodiment of the present application does not constitute a specific limitation to the UE 101. In other embodiments of the present application, the UE101 may include more or fewer components than illustrated, or combine certain components, or split certain components, or a different arrangement of components. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

Processor 1000 may include one or more processing units, such as: processor 1000 may include a Central Processing Unit (CPU), a Microprocessor (MCU), an Application Processor (AP), a modem Processor, a Graphics Processing Unit (GPU), a graphics Signal Processor (ISP), a controller, a video codec, a Digital Signal Processor (DSP), a baseband Processor, and/or a neural-Network Processing Unit (NPU), among others.

The modem is configured to modulate a baseband signal to be transmitted into a modulated signal that can be transmitted through the antenna according to a 3GPP protocol, and demodulate a signal received by the antenna into a baseband signal that can be processed by the processor of the UE 101. The different processing units may be separate devices or may be integrated in one or more processors.

The processor can generate an operation control signal according to the instruction operation code and the timing signal to complete the control of instruction fetching and instruction execution.

A memory may also be provided in processor 1000 for storing instructions and data. In some embodiments, the memory in processor 1000 is a cache memory. The memory may hold instructions or data that have just been used or recycled by processor 1000. If the processor 1000 needs to reuse the instruction or data, it can be called directly from the memory. Avoiding repeated accesses reduces the latency of the processor 1000, thereby increasing the efficiency of the system.

In some embodiments, processor 1000 may include one or more interfaces. The interface may include an integrated circuit (I2C) interface, an integrated circuit built-in audio (I2S) interface, a Pulse Code Modulation (PCM) interface, a universal asynchronous receiver/transmitter (UART) interface, a Mobile Industry Processor Interface (MIPI), a general-purpose input/output (GPIO) interface, and a Subscriber Identity Module (SIM) interface.

The wireless communication function of the UE101, for example, the cell search method according to the embodiment of the present application, can be implemented by the antenna 1, the antenna 2, the mobile communication module 150, the wireless communication module 160, the modem processor, the baseband processor, and the like.

The antennas 1 and 2 are used for transmitting and receiving electromagnetic wave signals. Each antenna in the UE101 may be used to cover a single or multiple communication bands. Different antennas can also be multiplexed to improve the utilization of the antennas. For example: the antenna 1 may be multiplexed as a diversity antenna of a wireless local area network. In other embodiments, the antenna may be used in conjunction with a tuning switch.

The mobile communication module 150 may provide a solution for wireless communication including 2G/3G/4G/5G, etc. applied on the UE 101. The mobile communication module 150 may include at least one filter, a switch, a power amplifier, a Low Noise Amplifier (LNA), and the like. The mobile communication module 150 may receive the electromagnetic wave from the antenna 1, filter, amplify, etc. the received electromagnetic wave, and transmit the electromagnetic wave to the modem processor for demodulation. The mobile communication module 150 may also amplify the signal modulated by the modem processor, and convert the signal into electromagnetic wave through the antenna 1 to radiate the electromagnetic wave. In some embodiments, at least some of the functional modules of the mobile communication module 150 may be disposed in the processor 1000. In some embodiments, at least some of the functional modules of the mobile communication module 150 may be disposed in the same device as at least some of the modules of the processor 1000. As shown in fig. 5, the NAS layer, the RRC layer, and the PHY layer described above according to an embodiment of the present application may be provided as functional modules in the mobile communication module 150.

The modem processor may include a modulator and a demodulator. The modulator is used for modulating a low-frequency baseband signal to be transmitted into a medium-high frequency signal. The demodulator is used for demodulating the received electromagnetic wave signal into a low-frequency baseband signal. The demodulator then passes the demodulated low frequency baseband signal to a baseband processor for processing. The low frequency baseband signal is processed by the baseband processor and then transferred to the application processor. The application processor outputs a sound signal through an audio device (not limited to the speaker 170A, the receiver 170B, etc.) or displays an image or video through the display screen 194. In some embodiments, the modem processor may be a stand-alone device. In other embodiments, the modem processor may be separate from the processor 1000, and may be disposed in the same device as the mobile communication module 150 or other functional modules.

In some embodiments, the antenna 1 of the UE101 is coupled to the mobile communication module 150 and the antenna 2 is coupled to the wireless communication module 160 so that the UE101 can communicate with the network and other devices via wireless communication techniques. The wireless communication technology may include global system for mobile communications (GSM), General Packet Radio Service (GPRS), code division multiple access (code division multiple access, CDMA), Wideband Code Division Multiple Access (WCDMA), time-division code division multiple access (time-division code division multiple access, TD-SCDMA), Long Term Evolution (LTE), LTE, BT, GNSS, WLAN, NFC, FM, and/or IR technologies, etc.

The external memory interface 120 may be used to connect an external memory card, such as a Micro SD card, to extend the storage capability of the UE 101. The external memory card communicates with the processor 1000 through the external memory interface 120 to implement a data storage function. For example, files such as music, video, etc. are saved in an external memory card. In an embodiment of the present application, the cell search parameter table may be stored in an external memory card connected through the external memory interface 120.

The internal memory 121 may be used to store computer-executable program code, which includes instructions. The internal memory 121 may include a program storage area and a data storage area. The storage program area may store an operating system, an application program (such as a sound playing function, an image playing function, and the like) required by at least one function, and the like. The stored data area may store data (e.g., audio data, phone book, etc.) created during use of the UE101, and the like. In addition, the internal memory 121 may include a high-speed random access memory, and may further include a nonvolatile memory, such as at least one magnetic disk storage device, a flash memory device, a universal flash memory (UFS), and the like. The processor 1000 executes various functional applications of the UE101 and data processing by executing instructions stored in the internal memory 121 and/or instructions stored in a memory disposed in the processor. In an embodiment of the present application, the internal memory 121 may be used to store a cell search parameter table, and the processor 1000 may be configured to perform a cell search method according to the embodiments shown in fig. 3-4.

The SIM card interface 195 is used to connect a SIM card. The SIM card can be brought into and out of contact with the UE101 by being inserted into the SIM card interface 195 or pulled out of the SIM card interface 195. The UE101 may support 1 or N SIM card interfaces, with N being a positive integer greater than 1. The SIM card interface 195 may support a Nano SIM card, a Micro SIM card, a SIM card, etc. Multiple cards can be inserted into the same SIM card interface 195 at the same time. The types of the plurality of cards may be the same or different. The SIM card interface 195 may also be compatible with different types of SIM cards. The SIM card interface 195 may also be compatible with external memory cards. The UE101 interacts with the network through the SIM card to realize functions such as conversation, data communication and the like. In some embodiments, the UE101 employs eSIM, namely: an embedded SIM card. The eSIM card can be embedded in the UE101 and cannot be separated from the UE 101. In an embodiment of the present application, information of a wireless communication network such as a PLMN may be stored in the SIM card.

The method embodiments of the present application may be implemented in software, magnetic, firmware, etc.

Program code may be applied to input instructions to perform the functions described herein and generate output information. The output information may be applied to one or more output devices in a known manner. For purposes of this application, a processing system includes any system having a processor such as, for example, a Digital Signal Processor (DSP), a microcontroller, an Application Specific Integrated Circuit (ASIC), or a microprocessor.

The program code may be implemented in a high level procedural or object oriented programming language to communicate with a processing system. The program code can also be implemented in assembly or machine language, if desired. Indeed, the mechanisms described herein are not limited in scope to any particular programming language. In any case, the language may be a compiled or interpreted language.

One or more aspects of at least one embodiment may be implemented by representative instructions stored on a computer-readable storage medium, which represent various logic in a processor, which when read by a machine causes the machine to fabricate logic to perform the techniques described herein. These representations, known as "IP cores" may be stored on a tangible computer-readable storage medium and provided to a number of customers or manufacturing facilities to load into the manufacturing machines that actually make the logic or processor.

While the description of the present application will be described in conjunction with the preferred embodiments, it is not intended that the features of the present application be limited to this embodiment. Rather, the invention has been described in connection with embodiments for the purpose of covering alternatives and modifications as may be extended based on the claims of the present application. In the following description, numerous specific details are included to provide a thorough understanding of the present application. The present application may be practiced without these particulars. Moreover, some of the specific details have been omitted from the description in order to avoid obscuring or obscuring the focus of the present application. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

Further, various operations will be described as multiple discrete operations, in a manner that is most helpful in understanding the illustrative embodiments; however, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.

As used herein, the term "module" or "unit" may refer to, be, or include: an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and/or memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

In the drawings, some features of the structures or methods are shown in a particular arrangement and/or order. However, it is to be understood that such specific arrangement and/or ordering may not be required. In some embodiments, these features may be arranged in a manner and/or order different from that shown in the illustrative figures. Additionally, the inclusion of structural or methodical features in a particular figure is not meant to imply that such features are required in all embodiments, and in some embodiments, these features may not be included or may be combined with other features.

Embodiments of the mechanisms disclosed herein may be implemented in hardware, software, firmware, or a combination of these implementations. Embodiments of the application may be implemented as computer programs or program code executing on programmable systems comprising multiple processors, a storage system (including volatile and non-volatile memory and/or storage elements), multiple input devices, and multiple output devices.

The program code may be implemented in a high level procedural or object oriented programming language to communicate with a processing system. The program code can also be implemented in assembly or machine language, if desired. Indeed, the mechanisms described in this application are not limited in scope to any particular programming language. In any case, the language may be a compiled or interpreted language.

In some cases, the disclosed embodiments may be implemented in hardware, firmware, software, or any combination thereof. In some cases, one or more aspects of at least some embodiments may be implemented by representative instructions stored on a computer-readable storage medium, which represent various logic within a processor, which when read by a machine causes the machine to fabricate logic to perform the techniques described herein. These representations, known as "IP cores" may be stored on a tangible computer-readable storage medium and provided to a number of customers or manufacturing facilities to load into the manufacturing machines that actually make the logic or processor.

Such computer-readable storage media may include, but are not limited to, non-transitory tangible arrangements of articles of manufacture or formation by machines or devices that include storage media such as: hard disk any other type of disk including floppy disks, optical disks, compact disk read-only memories (CD-ROMs), compact disk rewritables (CD-RWs), and magneto-optical disks; semiconductor devices such as Read Only Memory (ROM), Random Access Memory (RAM) such as Dynamic Random Access Memory (DRAM) and Static Random Access Memory (SRAM), Erasable Programmable Read Only Memory (EPROM), flash memory, Electrically Erasable Programmable Read Only Memory (EEPROM); phase Change Memory (PCM); magnetic or optical cards; or any other type of media suitable for storing electronic instructions.

Thus, embodiments of the present application also include non-transitory computer-readable storage media that contain instructions or that contain design data, such as Hardware Description Language (HDL), that define the structures, circuits, devices, processors, and/or system features described herein.

Claims

1. A synchronization method for a first user equipment, comprising:

acquiring a Global Navigation Satellite System (GNSS) signal from a GNSS Satellite and generating a pulse per second (1pps) signal;

selecting one synchronization mode from a plurality of synchronization modes as a synchronization mode of the first user equipment at least partially according to the GNSS signal and the 1pps signal, and synchronizing the first user equipment with a synchronization reference source corresponding to the synchronization mode of the first user equipment, wherein the plurality of synchronization modes comprise a satellite synchronization mode with the GNSS as the synchronization reference source and a reference UE synchronization mode with a second user equipment as the synchronization reference source.

2. The synchronization method of claim 1, wherein the plurality of synchronization modes further comprises a self-synchronization mode with the first user device as the synchronization reference source.

3. The synchronization method according to claim 1 or 2, wherein the selecting one synchronization mode from a plurality of synchronization modes as the synchronization mode of the first user equipment based at least in part on the GNSS signal and the 1pps signal comprises:

selecting the satellite synchronization mode as the synchronization mode of the first user equipment when the number of the GNSS satellites is equal to or greater than a first threshold value, a Reference Signal Power Level (Reference Signal Power Level) of the GNSS satellites is equal to or greater than a second threshold value, and a period of the 1pps Signal is 1s or the period is within a set range.

4. The synchronization method according to claim 1 or 2, wherein the selecting one synchronization mode from a plurality of synchronization modes as the synchronization mode of the first user equipment based at least in part on the GNSS signal and the 1pps signal comprises:

determining whether a Sidelink Reference Signal received Power (S-RSRP) from the second user equipment is greater than or equal to a third threshold in at least one of the following cases; wherein the following cases include: the number of the GNSS satellites is smaller than a first threshold, the Reference Signal Power Level (Reference Signal Power Level) of the GNSS satellites is smaller than a second threshold, and the period of the 1pps Signal is not 1s or is not in a set range;

selecting the reference UE synchronization pattern as the synchronization pattern of the first user equipment if it is determined that the reference signal received power from the second user equipment is greater than or equal to the third threshold.

5. The synchronization method of claim 4, wherein selecting one of a plurality of synchronization modes as the synchronization mode for the first user equipment based at least in part on the GNSS signal and a 1pps signal comprises:

selecting the self-synchronization mode as the synchronization mode of the first user equipment if it is determined that the reference signal received power from the second user equipment is less than the third threshold.

6. The synchronization method according to any one of claims 3 to 5, wherein the set range of the period of the 1pps signal is 1s ± 100 ns.

7. An on-board unit for a first user device, comprising:

a Global Navigation Satellite System (GNSS) unit for acquiring a GNSS signal from the GNSS and generating a 1pps signal;

a modulation and demodulation unit, configured to select one synchronization mode from multiple synchronization modes as a synchronization mode of the first user equipment at least partially according to the GNSS signal and the 1pps signal, and synchronize the first user equipment with a synchronization reference source corresponding to the selected one synchronization mode, where the multiple synchronization modes include a satellite synchronization mode in which the GNSS is used as the synchronization reference source and a reference UE synchronization mode in which a second user equipment is used as the synchronization reference source.

8. The on-board unit of claim 7, wherein the plurality of synchronization modes further includes a self-synchronization mode with the first user device as the synchronization reference source.

9. The on-board unit of claim 7 or 8, wherein the selecting a synchronization mode from a plurality of synchronization modes as the synchronization mode for the first user device based at least in part on the GNSS signal and the 1pps signal comprises:

selecting the satellite synchronization mode as the synchronization mode of the first user equipment when the number of the GNSS satellites is equal to or greater than a first threshold value, a Reference Signal Power Level (Reference Signal Power Level) of the GNSS satellites is equal to or greater than a second threshold value, and a period of the 1pps Signal is within a set range.

10. The on-board unit of claim 7 or 8, wherein the selecting a synchronization mode from a plurality of synchronization modes as the synchronization mode for the first user device based at least in part on the GNSS signal and the 1pps signal comprises:

determining whether a Sidelink Reference Signal received Power (S-RSRP) from the second user equipment is greater than or equal to a third threshold in at least one of the following cases; wherein the following cases include: the number of the GNSS satellites is smaller than a first threshold, the Reference Signal Power Level (Reference Signal Power Level) of the GNSS satellites is smaller than a second threshold, and the period of the 1pps Signal is not in a set range;

11. The on-board unit according to claim 9 or 10, wherein the set range of the period of the 1pps signal is 1s ± 100 ns.

12. The on-board unit of any of claims 9-11, wherein the selecting a synchronization mode from a plurality of synchronization modes as the synchronization mode for the first user device based at least in part on the GNSS signal and a 1pps signal comprises:

13. A computer-readable storage medium, wherein the storage medium is configured to store computer instructions, which when executed, implement the method of any one of claims 1-6.

14. A first user device, comprising:

a processor;

a memory for storing computer instructions that, when executed by the processor, may cause the first user equipment device to perform the method of any of claims 1-6.