CN106686714B

CN106686714B - Clock synchronizing method, synchronizing information method and device

Info

Publication number: CN106686714B
Application number: CN201510746483.4A
Authority: CN
Inventors: 周海军; 赵丽; 李媛媛; 赵毅
Original assignee: China Academy of Telecommunications Technology CATT
Current assignee: China Academy of Telecommunications Technology CATT; Datang Mobile Communications Equipment Co Ltd
Priority date: 2015-11-05
Filing date: 2015-11-05
Publication date: 2019-07-26
Anticipated expiration: 2035-11-05
Also published as: WO2017076195A1; CN106686714A

Abstract

The invention discloses a kind of clock synchronizing method, synchronizing information method and devices.It in the present invention, is synchronized for clock and defines two schemes, synchronization level is defined in every kind of clock synchronization scheme and enter the condition of different synchronization levels, to realize that clock is synchronous.In the present invention, for synchronizing information transmission plan, provide the following contents: if terminal receives the broadcast message of base station transmission, synchronous signal sequence is then obtained according to the broadcast message, otherwise, synchronous signal sequence is obtained from preconfigured synchronous signal sequence set according to the synchronization level of the terminal；The terminal determines the synchronization subframe for sending synchronizing information according to itself synchronization level.With this solution, synchronizing information transmission may be implemented, and isochronous resources conflict can be reduced.

Description

Clock synchronization method, synchronization information transmission method and device

Technical Field

The present invention relates to the field of wireless communications, and in particular, to a clock synchronization method, a synchronization information transmission method, and an apparatus.

Background

Clock synchronization is of great importance to communication networks. When a sending end sends a digital pulse signal, the digital pulse signal is placed at a specific time position (i.e. in a specific time slot), and a receiving end needs to extract and interpret the pulse at the specific time position to ensure normal communication at the receiving end and the sending end. This function of ensuring that both the transmitting and receiving terminals can correctly extract/transmit information at a specific time position is realized by the timing clocks at both the transmitting and receiving terminals. Therefore, the purpose of clock synchronization is to limit the clock frequency and phase of each node in the network within a predetermined tolerance range, so as to avoid the degradation of transmission performance (such as bit error, jitter, etc.) caused by the inaccuracy of transceiving positioning.

Taking D2D (Device-to-Device) communication system as an example, the D2D communication system is a short-range communication service, and can realize direct transmission of data between terminals. The combination of the D2D communication system and the cellular communication system can increase the spectrum efficiency of the cellular communication system, reduce the terminal transmission power and shorten the delay. In a scenario where the D2D communication system is combined with a cellular communication system, the D2D terminal performs clock synchronization by receiving synchronization information transmitted by a base station or other D2D terminals.

In view of the communication system, especially in view of the scenario of combining the D2D communication system with the cellular communication system, how to perform clock synchronization and further perform synchronization information transmission is a problem that needs to be solved at present.

Disclosure of Invention

In a first aspect, some embodiments of the present invention provide a clock synchronization method and apparatus, so as to implement clock synchronization.

An embodiment of a first aspect of the present invention provides a clock synchronization method, including:

if the terminal receives a time service signal of the UTC system, the UTC system is used as a synchronization source to carry out clock synchronization, and the UTC system enters a synchronization level 1; otherwise, if the synchronous signal is received within the first time period, performing clock synchronization by using the terminal or the base station which sends the synchronous signal as a synchronous source according to the grade of the synchronous signal.

Preferably, if the synchronization signal is received within the first time period, performing clock synchronization with the base station that transmits the synchronization signal as a synchronization source according to the level of the synchronization signal includes: if the time service signal of the UTC system is not received within the first time length, but the downlink pilot signal sent by the base station of the synchronization level 0 is received, then:

taking the base station with the synchronization level 0 as a synchronization source, performing clock synchronization on the basis of performing timing compensation based on distance calibration or uplink synchronization calibration, and entering a synchronization level 2; or,

performing clock synchronization by using the base station as a synchronization source, and entering a synchronization level 2 or a synchronization level 3 according to a timing compensation enabling mark configured by the base station, wherein the timing compensation enabling mark is used for indicating whether timing compensation is enabled or not; if the timing compensation is enabled and the terminal performs clock synchronization based on the timing compensation performed by the distance calibration or the uplink synchronization calibration, the terminal enters a synchronization level 2, otherwise, the terminal enters a synchronization level 3, and if the timing compensation is not enabled, the terminal enters the synchronization level 2;

wherein, the base station of synchronization level 0 refers to: and a base station which is synchronized with the UTC system and can broadcast the offset of the downlink pilot signal and the UTC clock.

Preferably, if the synchronization signal is received within the first time period, performing clock synchronization with a terminal that transmits the synchronization signal as a synchronization source according to a level of the synchronization signal, including:

if a synchronization signal sent by a terminal of a synchronization level 1 is received within a first time period, performing clock synchronization by taking the terminal of the synchronization level 1 as a synchronization source, and entering a synchronization level 2; or,

if the synchronization signal sent by the terminal of the synchronization level 1 is not received within the first time length, but the synchronization signal sent by the terminal of the synchronization level 2 is received, performing clock synchronization by taking the terminal of the synchronization level 2 as a synchronization source, and entering a synchronization level 3; or,

if only the synchronization signal sent by the synchronization level 3 is received within the first duration, performing clock synchronization according to all the synchronization signals of the synchronization level 3 received in N synchronization periods, or performing clock synchronization by using a terminal with the front time as a synchronization source in a source terminal of the synchronization signal of the synchronization level 3 received in the N synchronization periods, and entering the synchronization level 3, wherein N is an integer greater than or equal to 1; the synchronization signal of synchronization level 3 includes a synchronization signal sent by a terminal and/or a base station of synchronization level 3, and the base station of synchronization level 3 refers to: a base station that is not clock-synchronized with the UTC system or a base station that cannot obtain its own position.

Preferably, the method further comprises the following steps: and if the time service signal of the UTC system is not received in the first time period and the synchronization signal sent by the base station or other terminals is not received, entering a synchronization level 3 when a second time period after the first time period is up.

Preferably, the method further comprises the following steps: and if the terminal entering the synchronization level 1 receives the synchronization signal sent by the base station or other terminals, giving up the clock synchronization by taking the base station or other terminals sending the synchronization signal as a synchronization source.

An embodiment of the first aspect of the present invention further provides a terminal, including: a receiving module and a synchronization module;

the synchronization module is used for performing clock synchronization by using the universal coordinated time (UTC) system as a synchronization source and entering a synchronization level 1 if the receiving module receives a time service signal of the UTC system; otherwise, if the receiving module receives the synchronous signal within the first time length, the terminal or the base station which sends the synchronous signal is used as a synchronous source to carry out clock synchronization according to the grade of the synchronous signal.

Preferably, the synchronization module is specifically configured to:

if the receiving module does not receive the time service signal of the UTC system within the first time length, but receives the downlink pilot signal sent by the base station with the synchronization level of 0, then:

performing clock synchronization by using the base station as a synchronization source, and entering a synchronization level 2 or a synchronization level 3 according to a timing compensation enabling mark configured by the base station, wherein the timing compensation enabling mark is used for indicating whether timing compensation is enabled or not; if the timing compensation is enabled and the terminal performs clock synchronization based on the timing compensation performed by the distance calibration or the uplink synchronization calibration, entering a synchronization level 2, otherwise entering a synchronization level 3, and if the timing compensation is not enabled, entering the synchronization level 2;

Preferably, the synchronization module is specifically configured to:

if the receiving module receives a synchronization signal sent by a terminal of a synchronization level 1 within a first time length, performing clock synchronization by taking the terminal of the synchronization level 1 as a synchronization source, and entering a synchronization level 2; or,

if the receiving module does not receive the synchronization signal sent by the terminal of the synchronization level 1 within the first time length, but receives the synchronization signal sent by the terminal of the synchronization level 2, performing clock synchronization by taking the terminal of the synchronization level 2 as a synchronization source, and entering a synchronization level 3; or,

if the receiving module only receives the synchronization signals sent by the synchronization level 3 within the first duration, performing clock synchronization according to all the synchronization signals of the synchronization level 3 received in N synchronization periods, or performing clock synchronization by using a terminal with a front time as a synchronization source in a source terminal of the synchronization signals of the synchronization level 3 received in the N synchronization periods, and entering the synchronization level 3, wherein N is an integer greater than or equal to 1; the synchronization signal of synchronization level 3 includes a synchronization signal sent by a terminal and/or a base station of synchronization level 3, and the base station of synchronization level 3 refers to: a base station that is not clock-synchronized with the UTC system or a base station that cannot obtain its own position.

Preferably, the synchronization module is further configured to: and if the receiving module does not receive the time service signal of the UTC system in the first time length and does not receive the synchronous signal sent by the base station or other terminals, entering a synchronous grade 3 when a second time length after the first time length is up.

Preferably, the synchronization module is further configured to: and if the receiving module of the terminal entering the synchronization level 1 receives the synchronization signal sent by the base station or other terminals, giving up the clock synchronization by taking the base station or other terminals sending the synchronization signal as a synchronization source.

In the clock synchronization scheme provided in the embodiment of the first aspect of the present invention, if the terminal receives the time service signal of the UTC system, the UTC system is used as a synchronization source to perform clock synchronization, and the UTC system enters a synchronization level 1; otherwise, if the synchronous signal is received within the first time period, performing clock synchronization by using the terminal or the base station which sends the synchronous signal as a synchronous source according to the grade of the synchronous signal. It can be seen that, according to different situations, the terminal can enter different synchronization levels to achieve clock synchronization with different accuracies.

In a second aspect, another clock synchronization method and apparatus provided in the embodiments of the present invention are used to implement clock synchronization.

An embodiment of the second aspect of the present invention provides a clock synchronization method, including:

if the terminal receives a downlink pilot signal sent by a base station of a synchronization level 0, performing clock synchronization by using the base station of the synchronization level 0 as a synchronization source, and entering a synchronization level 1 a; otherwise, if receiving a synchronization signal sent by other terminals or a time service signal of the universal coordinated time (UTC) system within the first time period, performing clock synchronization by using the other terminals as synchronization sources or using the UTC system as a synchronization source according to the synchronization levels of the other terminals.

Preferably, if receiving a synchronization signal sent by another terminal within the first time period, performing clock synchronization with the another terminal as a synchronization source according to the synchronization level of the another terminal, including:

if a synchronization signal sent by a terminal of a synchronization level 1a is received within a first time period, performing clock synchronization by taking the terminal of the synchronization level 1a as a synchronization source, and entering a synchronization level 3; or,

if only a synchronization signal sent by a terminal with a synchronization level not higher than 1 is received within a first time length, wherein the terminal with the synchronization level not higher than 1 comprises a terminal with a synchronization level 1, performing clock synchronization by taking the terminal with the synchronization level 1 as a synchronization source, and entering a synchronization level 2; or,

if only a synchronization signal sent by a terminal with a synchronization level not higher than 2 is received within a first time length, and the terminal with the synchronization level not higher than 2 comprises a terminal with a synchronization level 2, performing clock synchronization by using the terminal with the synchronization level 2 as a synchronization source, and entering a synchronization level 3; or,

if only the synchronization signal sent by the terminal of the synchronization level 3 is received within the first duration, performing clock synchronization according to all the synchronization signals of the synchronization level 3 received in N synchronization periods, or performing clock synchronization by using a terminal with a previous time as a synchronization source in a source terminal of the synchronization signals of the synchronization level 3 received in the N synchronization periods, and entering the synchronization level 3, wherein N is an integer greater than or equal to 1.

Preferably, if the time service signal of the UTC system is received within the first time period, performing clock synchronization by using the UTC system as a synchronization source, including: and if the synchronization signal sent by the terminal of the synchronization level 1a is not received within the first time length, but the time service signal of the UTC system is received, performing clock synchronization by using the UTC system as a synchronization source, and entering the synchronization level 1.

Preferably, the method further comprises the following steps: and if the synchronization signal sent by the base station or other terminals is not received in the first time length, entering a synchronization level 3 when a second time length after the first time length is up.

An embodiment of a second aspect of the present invention provides a terminal, including: a receiving module and a synchronization module;

the synchronization module is configured to perform clock synchronization using the base station of the synchronization level 0 as a synchronization source and enter a synchronization level 1a if the receiving module receives a downlink pilot signal sent by the base station of the synchronization level 0; otherwise, if the receiving module receives a synchronization signal sent by other terminals or a time service signal of the universal coordinated time (UTC) system within the first time length, the other terminals are used as synchronization sources or the UTC system is used as a synchronization source to perform clock synchronization according to the synchronization levels of the other terminals.

Preferably, the synchronization module is specifically configured to:

if the receiving module receives a synchronization signal sent by a terminal of a synchronization level 1a within a first time length, performing clock synchronization by taking the terminal of the synchronization level 1a as a synchronization source, and entering a synchronization level 3; or,

if the receiving module only receives a synchronization signal sent by a terminal with a synchronization level not higher than 1 in a first time length, and the terminal with the synchronization level not higher than 1 comprises a terminal with a synchronization level 1, performing clock synchronization by using the terminal with the synchronization level 1 as a synchronization source, and entering a synchronization level 2; or,

if the receiving module only receives a synchronization signal sent by a terminal with a synchronization level not higher than 2 in a first time length, and the terminal with the synchronization level not higher than 2 comprises a terminal with a synchronization level 2, performing clock synchronization by using the terminal with the synchronization level 2 as a synchronization source, and entering a synchronization level 3; or,

if the receiving module only receives the synchronization signals sent by the terminals of the synchronization level 3 within the first duration, performing clock synchronization according to all the synchronization signals of the synchronization level 3 received in N synchronization periods, or performing clock synchronization by using the terminals with the earlier time as synchronization sources in the source terminals of the synchronization signals of the synchronization level 3 received in the N synchronization periods, and entering the synchronization level 3, wherein N is an integer greater than or equal to 1.

Preferably, the synchronization module is specifically configured to: if the receiving module does not receive the synchronization signal sent by the terminal of the synchronization level 1a within the first time length, but receives the time service signal of the UTC system, the UTC system is used as a synchronization source to carry out clock synchronization, and the UTC system enters the synchronization level 1.

Preferably, the synchronization module is further configured to: and if the receiving module does not receive the synchronization signal sent by the base station or other terminals in the first time length, entering a synchronization level 3 when a second time length after the first time length is up.

In the clock synchronization scheme provided in the embodiment of the second aspect of the present invention, when a downlink pilot signal sent by a base station of synchronization level 0 is received, the base station is used as a synchronization source to perform clock synchronization, and enters synchronization level 1 a; otherwise, if receiving the synchronization signal sent by other terminals or the time service signal of the UTC system within the first time period, performing clock synchronization by using the other terminals as synchronization sources or using the UTC system as a synchronization source according to the synchronization levels of the other terminals. It can be seen that, according to different situations, the terminal can enter different synchronization levels to achieve clock synchronization with different accuracies.

In a third aspect, an embodiment of the present invention further provides a clock synchronization method and apparatus, so as to reduce synchronization resource conflicts.

An embodiment of the third aspect of the present invention provides a synchronization information transmission method, including:

a terminal acquires a synchronous signal sequence to be sent; if the terminal receives a broadcast message sent by a base station, acquiring a synchronous signal sequence according to the broadcast message, otherwise, acquiring the synchronous signal sequence from a preset synchronous signal sequence set according to the synchronization level of the terminal;

the terminal determines a synchronous subframe for sending synchronous information according to the synchronous grade of the terminal;

and the terminal sends the synchronization information in the determined synchronization subframe, wherein the sent synchronization information comprises the acquired synchronization signal sequence.

Preferably, the preconfigured synchronization signal sequence set includes N subsets, where N is an integer greater than or equal to 3, and different synchronization levels correspond to different subsets;

the acquiring a synchronization signal sequence from a pre-configured synchronization signal sequence set according to the synchronization level of the terminal includes:

if the synchronization level of the terminal is 1, selecting a pre-agreed synchronization signal sequence from the subset corresponding to the synchronization level 1; or,

if the synchronization level of the terminal is 2, selecting a pre-agreed synchronization signal sequence from the subset corresponding to the synchronization level 2; or,

if the synchronization level of the terminal is 3 and the terminal does not perform clock synchronization with any synchronization source to enter the synchronization level 3, selecting a synchronization signal sequence from the subset corresponding to the synchronization level 3, and if the synchronization level of the terminal is 3 and the terminal performs clock synchronization with the synchronization source of which the synchronization level is not lower than the synchronization level 3 to enter the synchronization level 3, acquiring a synchronization signal sequence which is the same as or corresponding to the synchronization signal sequence sent by the synchronization source according to the synchronization source.

If the synchronization level of the terminal is 3 and the terminal enters the synchronization level 3 in a clock synchronization manner with a synchronization source of which the synchronization level is not lower than the synchronization level 3, acquiring a synchronization signal sequence which is the same as or corresponding to a synchronization signal sequence sent by the synchronization source according to the synchronization source, including:

if the synchronization level of the terminal is 3 and the terminal of the synchronization level 2 or the synchronization level 1a is used as a synchronization source to perform clock synchronization to enter the synchronization level 3, selecting a second synchronization signal sequence from a subset corresponding to the synchronization level 3 according to a first synchronization signal sequence sent by the terminal of the synchronization level 2 or the synchronization level 1a used as the synchronization source; the corresponding relation between the first synchronous signal sequence and the second synchronous signal sequence is predetermined; or,

and if the synchronization level of the terminal is 3 and the terminal of the synchronization level 3 is used as a synchronization source to perform clock entering into the synchronization level 3, taking a synchronization signal sequence sent by the terminal of the synchronization level 3 as the synchronization source as the synchronization signal sequence to be sent.

If the synchronization level of the terminal is 3 and the terminal with the synchronization level 1a is used as a synchronization source to perform clock synchronization and enter the synchronization level 3, selecting a second synchronization signal sequence from a subset corresponding to the synchronization level 3 according to a first synchronization signal sequence sent by the terminal with the synchronization level 1a as the synchronization source, wherein the corresponding relation between the first synchronization signal sequence and the second synchronization signal sequence is pre-configured or agreed;

the second synchronization signal sequence is transmitted in a synchronization subframe following a synchronization subframe occupied by the synchronization signal of the synchronization level 1 a.

Preferably, one synchronization period includes 3 synchronization subframes including a first synchronization subframe, a second synchronization subframe and a third synchronization subframe, the first synchronization subframe corresponds to a synchronization level 1 and a synchronization level 3, the second synchronization subframe corresponds to a synchronization level 2, and the third synchronization subframe corresponds to a synchronization level 3;

the terminal determines a synchronous subframe corresponding to the synchronous grade of the terminal as a synchronous subframe for sending synchronous information according to the synchronous grade of the terminal, and the method comprises the following steps:

if the synchronization level of the terminal is synchronization level 1, determining a first synchronization subframe as a synchronization subframe for sending synchronization information; or,

if the synchronization level of the terminal is synchronization level 2, determining a second synchronization subframe as a synchronization subframe for sending synchronization information; or,

if the synchronization level of the terminal is synchronization level 3 and the terminal can receive the synchronization signal sent by the terminal of synchronization level 2, determining a third synchronization subframe as a synchronization subframe for sending synchronization information; otherwise, determining the first synchronous subframe or the third synchronous subframe as the synchronous subframe for sending the synchronous information.

Preferably, one synchronization period includes 2 synchronization subframes including a first synchronization subframe and a second synchronization subframe, the first synchronization subframe corresponds to a synchronization level 1 and a synchronization level 3, and the second synchronization subframe corresponds to a synchronization level 2 and a synchronization level 3;

if the synchronization level of the terminal is synchronization level 3 and the terminal can receive the synchronization signal sent by the terminal of synchronization level 2, determining a first synchronization subframe as a synchronization subframe for sending synchronization information; otherwise, determining the first synchronous subframe or the second subframe as the synchronous subframe for sending the synchronous information.

Preferably, one synchronization period includes 2 synchronization subframes including a first synchronization subframe and a second synchronization subframe, the first synchronization subframe corresponds to a synchronization level 1, and the second synchronization subframe corresponds to a synchronization level 2;

and if the synchronization grade of the terminal is 3, giving up sending the synchronization information.

Preferably, the preset synchronization signal sequence set includes N subsets, where N is an integer greater than or equal to 3, and different synchronization levels correspond to different subsets;

the broadcast message sent by the base station carries indication information of a synchronization signal sequence, wherein:

the synchronization signal sequence corresponding to the synchronization level 1 or the synchronization level 1a is selected from the subset corresponding to the synchronization level 1;

the synchronization signal sequence corresponding to the synchronization level 2 is selected from the subset corresponding to the synchronization level 2;

the synchronization signal sequence corresponding to synchronization level 3 is selected from the subset corresponding to synchronization level 3.

The number of subsets included in the preconfigured synchronization signal sequence set is 3, the 3 subsets correspond to a synchronization level 1, a synchronization level 2 and a synchronization level 3, respectively, and the number of synchronization signal sequences in the subset corresponding to the synchronization level 3 is not less than the number of synchronization signal sequences in the subset corresponding to the synchronization level 2; or,

the pre-configured synchronization signal sequence set comprises a first subset and a second subset, the first subset comprises 2 subsets which respectively correspond to a synchronization level 1 and a synchronization level 2, the second subset corresponds to a synchronization level 3, and the number of the synchronization signal sequences in the second subset is not less than that of the synchronization signal sequences in the first subset.

Preferably, the synchronization information sent by the terminal further includes PBSCH content; the PBSCH content sent by the terminal is acquired from the broadcast message if the terminal receives the broadcast message sent by the base station, otherwise, the PBSCH content sent by the terminal is pre-configured; or,

the synchronization information sent by the terminal also comprises PBSCH content; the PBSCH content sent by the terminal is configured in advance if the terminal does not receive the broadcast message sent by the base station and does not receive the synchronization signal sent by the terminal of the synchronization level 1a, the PBSCH content sent by the terminal is acquired from the synchronization signal sent by the terminal of the synchronization level 1a if the terminal does not receive the broadcast message of the base station but receives the synchronization signal sent by the terminal of the synchronization level 1a, and the PBSCH content sent by the terminal is acquired from the broadcast message sent by the base station if the terminal receives the broadcast message sent by the base station.

Preferably, the method further comprises the following steps: and if the terminal detects that the used synchronous resources of the terminal conflict with the used synchronous resources of other terminals, the terminal selects a new idle subframe to send the synchronous information.

In the clock synchronization scheme provided in the above embodiment of the present invention, if the terminal receives the downlink pilot signal sent by the base station of synchronization level 0, the base station of synchronization level 0 is used as a synchronization source to perform clock synchronization, and enters synchronization level 1 a; otherwise, if the synchronization signal sent by other terminals or the time service signal of the UTC system is received in the first time period, the other terminals or the UTC system is used as a synchronization source to carry out clock synchronization. It can be seen that, according to different situations, the terminal can enter different synchronization levels to achieve clock synchronization with different accuracies.

An embodiment of a third aspect of the present invention provides a terminal, including:

the acquisition module is used for acquiring a synchronization signal sequence to be transmitted; if the terminal receives a broadcast message sent by a base station, acquiring a synchronous signal sequence according to the broadcast message, otherwise, acquiring the synchronous signal sequence from a preset synchronous signal sequence set according to the synchronization level of the terminal;

a determining module, configured to determine a synchronization subframe for sending synchronization information according to a synchronization level of the terminal;

and the sending module is used for sending the synchronization information in the determined synchronization subframe, wherein the sent synchronization information comprises the acquired synchronization signal sequence.

the acquisition module is specifically configured to:

Wherein the obtaining module is specifically configured to:

if the synchronization level of the terminal is 3 and the terminal with the synchronization level 1a is used as a synchronization source to perform clock synchronization and enter the synchronization level 3, selecting a second synchronization signal sequence from a subset corresponding to the synchronization level 3 according to a first synchronization signal sequence sent by the terminal with the synchronization level 1a as the synchronization source, wherein the corresponding relation between the first synchronization signal sequence and the second synchronization signal sequence is configured or agreed in advance;

the determining module is specifically configured to: when the synchronization subframe for sending the synchronization information is determined, determining a synchronization subframe behind the synchronization subframe occupied by the synchronization signal of the synchronization level 1a as the synchronization subframe for sending the synchronization information by the terminal.

the determining module is specifically configured to:

Preferably, the number of subsets included in the preconfigured synchronization signal sequence set is 3, the 3 subsets respectively correspond to a synchronization level 1, a synchronization level 2, and a synchronization level 3, and the number of synchronization signal sequences in the subset corresponding to the synchronization level 3 is not less than the number of synchronization signal sequences in the subset corresponding to the synchronization level 2; or,

Preferably, the determining module is further configured to: and if the synchronization resource used by the terminal is detected to conflict with the synchronization resource used by other terminals, selecting a new idle subframe to send synchronization information.

In the synchronization information transmission scheme provided in the embodiment of the third aspect of the present invention, on one hand, when a terminal acquires a synchronization signal sequence to be sent, if the terminal receives a broadcast message sent by a base station, the terminal acquires the synchronization signal sequence according to the broadcast message, otherwise, the terminal acquires the synchronization signal sequence from a synchronization signal sequence set configured in advance according to a synchronization level of the terminal, so as to determine the synchronization signal sequence that the terminal needs to send according to a network coverage condition of the terminal; on the other hand, when the terminal determines the synchronization subframe for sending the synchronization information, the used synchronization subframe can be determined according to the synchronization level determination of the terminal, that is, the corresponding relationship can exist between the synchronization level and the synchronization subframe, so that the terminals with different synchronization levels can send the synchronization information by using different synchronization subframes, and further, the synchronization resource conflict can be reduced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a schematic flowchart of a first clock synchronization scheme according to an embodiment of the present invention;

fig. 2 is a schematic flow chart of a second clock synchronization scheme according to an embodiment of the present invention;

fig. 3 is a schematic diagram of a synchronization information transmission flow according to an embodiment of the present invention;

fig. 4 is a schematic diagram of frequency domain resources occupied by synchronization information according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a terminal according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a terminal according to another embodiment of the present invention;

fig. 7 is a schematic structural diagram of a terminal according to another embodiment of the present invention;

fig. 8 is a schematic structural diagram of a terminal according to another embodiment of the present invention;

fig. 9 is a schematic structural diagram of a terminal according to another embodiment of the present invention;

fig. 10 is a schematic structural diagram of a terminal according to another embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As mentioned above, clock synchronization is of great significance to communication networks, and especially in the scenario where the D2D communication system is combined with a cellular communication system, the cellular coverage of the terminal is various, so the influence of the clock synchronization scheme on the communication performance is more important.

Taking the car networking system in the D2D communication system as an example, the car networking system takes a car as a basic information unit, and utilizes advanced sensing technology, information acquisition technology, access technology, transmission technology and networking technology to comprehensively sense roads and traffic, so as to realize interaction of large-range and large-capacity data among multiple systems, thereby providing network and application of traffic efficiency and traffic safety. The internet of vehicles has node characteristics, mobility characteristics, and data flow characteristics. The mobile characteristic of the method is characterized by fast change of network topology, fast moving speed of nodes and the like. In the process of high-speed movement of the terminal, part of the terminals may be in the coverage range of the cell, part of the terminals may be outside the coverage of the cell, and part of the terminals may be at the edge of the coverage of the cell, i.e., there may be an in-coverage terminal, a part of an in-coverage terminal, and an out-coverage terminal.

Wherein, the related explanations of the covered inner terminal, the partially covered terminal and the covered outer terminal are as follows:

-in-coverage terminal: an in-coverage terminal of a cellular network is able to successfully demodulate the broadcast message of the cellular network.

-partial coverage terminal: a partial-coverage terminal of a cellular network may not successfully demodulate the broadcast messages of the cellular network, but may receive the synchronization signal transmitted by the terminal within the cellular network coverage and may successfully demodulate the physical broadcast channel transmitted by the terminal within the cellular network coverage.

-an overlay outer terminal: an out-of-coverage terminal of a cellular network cannot successfully demodulate the broadcast message of the cellular network, nor can it receive the synchronization signal transmitted by the in-coverage terminal of the cellular network or successfully demodulate the physical broadcast channel transmitted by the in-coverage terminal of the cellular network. For example, the case where the out-of-coverage terminal receives the synchronization information may include: only the synchronization signal and the physical broadcast channel transmitted by the partially covered terminal can be received, or only the synchronization signal and the physical broadcast channel transmitted by the out-of-coverage terminal can be received, or the synchronization signal and the physical broadcast channel transmitted by any terminal cannot be received.

The embodiment of the invention provides a clock synchronization scheme and a synchronization information transmission scheme, wherein the clock synchronization scheme provides definition of synchronization levels and how to perform clock synchronization, and the synchronization information transmission scheme provides how to determine the content of synchronization information to be sent and how to allocate transmission resources of the synchronization information by a terminal. The two schemes can be independent of each other (for example, the definition of the synchronization level involved in the "synchronization information transmission scheme" may be different from that in the "clock synchronization scheme"), or can be related (for example, the definition of the synchronization level involved in the "synchronization information transmission scheme" is the same as that in the "clock synchronization scheme").

In specific implementation, the synchronization at the sub-frame level may be implemented according to a "clock synchronization scheme", and then the transmission of the synchronization information may be implemented according to a "synchronization information transmission scheme". The "clock synchronization scheme" and the "synchronization information transmission scheme" are described below, respectively.

The embodiment of the invention can be suitable for different types of communication systems needing clock synchronization, and is particularly suitable for a system architecture combining a D2D communication system and a cellular communication system.

In the following description, a specific implementation procedure of the embodiment of the present invention is described by taking a scenario in which a D2D communication system is combined with cellular communication as an example, and all terminals involved in the following embodiments are D2D terminals unless otherwise specified. Of course, the specific implementation described below is applicable to other types or architectures of communication systems.

The following first describes a clock synchronization scheme provided by an embodiment of the present invention. Generally, the embodiments of the present invention provide two clock synchronization schemes (e.g., a first clock synchronization scheme and a second clock synchronization scheme described below), and different clock synchronization schemes provide different synchronization level definitions and clock synchronization modes. The base station can indicate which clock synchronization scheme is adopted by the terminal, and the terminal can also adopt the clock synchronization scheme appointed by the system according to the system appointment. In case that the base station instructs the terminal which clock synchronization scheme to adopt, the base station may transmit an enable flag to the terminal through a broadcast message, the enable flag being used to instruct the terminal which clock synchronization scheme to adopt. For example, the enable flag is denoted as G, and if G is 1, it denotes that the first clock synchronization scheme is adopted, and if G is 0, it denotes that the second clock synchronization scheme is adopted.

Clock synchronization scheme one

In the first clock synchronization scheme, 4 synchronization levels are defined, and the 4 synchronization levels are respectively called as follows according to the sequence from high to low: sync level 0, sync level 1, sync level 2, and sync level 3. Wherein, the synchronization level 0 may be dedicated to the base station, the synchronization level 1 and the synchronization level 2 may be dedicated to the terminal, and the synchronization level 3 may be used for the base station and the terminal. Generally, the higher the synchronization level, the higher the synchronization accuracy.

It should be noted that the naming manner of the 4 synchronization levels is only an example, and other naming manners, such as the synchronization level 1 being referred to as a first synchronization level, the synchronization level 2 being referred to as a second synchronization level, and so on, may also be adopted in the embodiments of the present invention.

(1) Synchronization level 0

If the base station performs clock synchronization with a UTC (Universal Time Coordinated) system, and can broadcast the offset of the downlink pilot signal and the UTC clock, for example, the offset of the downlink synchronization clock and the UTC clock can be notified through a system broadcast message, because the crystal oscillator of the base station has the characteristics of high stability and large transmission power, the base station can provide a synchronization source of a clock and a frequency with a large coverage range and high stability for a terminal under cellular coverage, and at this Time, the synchronization level of the base station is defined as level 0.

(2) Synchronization level 1

If the terminal can receive the time service signal of the UTC system and performs clock synchronization by using the UTC system as a synchronization source, the synchronization level of the terminal is synchronization level 1.

Further, when the terminal entering the synchronization level 1 receives the synchronization signal transmitted from the base station or another terminal, the terminal abandons the clock synchronization using the base station or another terminal that transmitted the synchronization signal as a synchronization source. That is, a terminal capable of obtaining a UTC clock by a UTC time service system such as a satellite does not need to obtain its transmission clock by a base station, and only the UTC time service system such as a satellite is used as its clock source.

(3) Synchronization level 2

In one scenario, if a terminal receives a downlink pilot signal sent by a base station of a synchronization level 0, and the terminal performs clock synchronization based on timing compensation based on distance calibration or uplink synchronization calibration with the base station as a synchronization source, the synchronization level of the terminal is synchronization level 2.

In another scenario, a timing compensation enabling flag is configured on the terminal, and for convenience of description, the timing compensation enabling flag is described as TC. The TC may be configured by the base station to the terminal, or may be system-agreed. The TC is used to indicate whether the terminal enables the operation of timing compensation when performing clock synchronization, for example, when TC is 0, it means that timing compensation is enabled, and when TC is 1, it means that timing compensation is not enabled. In this case, if the terminal receives a downlink pilot signal transmitted by the base station of synchronization level 0, then:

-if the terminal is capable of performing clock synchronization based on timing compensation based on distance calibration or uplink synchronization calibration with the base station of synchronization level 0 as the synchronization source and is clock synchronized based on said timing compensation, with timing compensation enabled, the synchronization level of the terminal is 2; otherwise, if the terminal cannot perform clock synchronization based on the timing compensation, but performs general clock synchronization (i.e., does not perform the timing compensation) with the base station of the synchronization level 0 as a synchronization source, the synchronization level of the terminal is 3;

-the terminal has a synchronization level of 2 after it has performed clock synchronization with the base station of synchronization level 0 as synchronization source, in case timing compensation is not enabled.

The timing compensation method may include performing timing compensation based on distance calibration and performing timing compensation based on uplink synchronization calibration. Wherein the terminal transmission clock t0 is equal to the clock t1- τ 1 of the received base station signal after the timing compensation based on the distance calibration, whereinL' bu is the estimated distance from the terminal to the base station (the base station informs the coordinate position of the base station in the system broadcast message, and can calculate the spatial distance from the terminal to the base station if the terminal position is also known), and C is the speed of light; when the terminal under the coverage of the base station cannot realize positioning, distance-based calibration cannot be carried out, but when the terminal establishes uplink synchronization with the network, the terminal transmission clock t0 is equal to the clock t1-TA/2 of the received base station signal, wherein if t2 is the cellular uplink transmission clock, TA is t1-t 2.

In another scenario, if a terminal receives a synchronization signal sent by a terminal of synchronization level 1 and performs clock synchronization with the terminal of synchronization level 1 as a synchronization source, the synchronization level of the terminal is synchronization level 2.

(4) Synchronization level 3

For a base station, if the base station is not clock-synchronized with the UTC system or cannot obtain its own position, the synchronization level of the base station is 3. A GNSS (Global navigation satellite System, or Global navigation satellite System) can be placed near the radio-frequency antenna of the base station, so that the position information can be obtained by the GNSS. If the base station is not equipped with a GNSS or other equipment, the self position information can not be obtained.

As described above, in a scenario where the timing compensation enable flag TC is provided at the terminal, if the terminal receives the downlink pilot signal transmitted from the base station of synchronization level 0, and if the timing compensation is enabled, the terminal cannot perform clock synchronization based on the timing compensation and performs general clock synchronization (that is, does not perform the timing compensation) with the base station of synchronization level 0 as a synchronization source, the synchronization level of the terminal is 3.

In another scenario, if a terminal receives a synchronization signal sent by a terminal of synchronization level 2 and performs clock synchronization with the terminal of synchronization level 2 as a synchronization source, the synchronization level of the terminal is synchronization level 3.

In another scenario, if the terminal receives only the transmitted synchronization signal of synchronization level 3 and performs self-synchronization according to the synchronization signal of synchronization level 3 received in N (N is an integer greater than or equal to 1) synchronization periods, the synchronization level of the terminal is synchronization level 3. The synchronization signal of the synchronization level 3 comprises a synchronization signal transmitted by a terminal of the synchronization level 3 and/or a base station of the synchronization level 3.

Preferably, the self-synchronizing mode includes the following two modes:

self-synchronization method 1: and carrying out weighted summation on the receiving clocks of all the synchronization signals of the synchronization level 3 received in the N synchronization periods, and obtaining an average value result as a sending clock.

For example, in N synchronization periods, when a terminal i receives synchronization signals transmitted by K synchronization level 3 terminals, the terminal i uses the 1ms data transmission start point T of the terminal as a reference, uses the reception start points Tx and T of other terminals for 1ms data to make a difference, and performs a modulo operation on the difference and 1ms to obtain the normalized clock Tx of the K synchronization level 3 terminals (i.e., T1, T2, T3 … … tk, where the normalized clock difference of the terminal i is T0 ═ 0):

tx＝Mod(Tx-T,1ms)………………………………(1)

then, the terminal i calculates a transmission clock adjustment amount △ i of the terminal itself according to the following formula, thereby adjusting the local clock of the terminal i according to △ i:

where ax is a weight of the clock adjustment amount, and ax may be a received power of the corresponding synchronization signal. a0 can be selected fromR is more than or equal to 0, the clock adjustment rate of the terminal can be controlled through R, and the specific value can be determined through simulation.

Thus, when the terminal i can only receive the synchronization signal of the synchronization level 3, the transmission clock of the terminal i is adjusted according to the above manner every N synchronization cycles, and the clock adjustment rate of the terminal can be further controlled by the value of R, so that the clock synchronization precision can be improved as much as possible under the condition that a high synchronization level synchronization source cannot be obtained.

Self-synchronization method 2: and taking the terminal in the front time as a synchronization source to perform clock synchronization in the source terminal of the synchronization signal of the synchronization level 3 received in the N synchronization periods.

In another scenario, if the terminal does not receive the synchronization signal sent by the base station or other terminals, after delaying for a certain time length after the set time length, the terminal enters synchronization level 3. The time length of the required delay can be predetermined or configured by the base station, and the value of the time length can be determined according to needs or system simulation or experience.

In the first clock synchronization scheme, if the terminal can receive a synchronization signal sent by the base station or other terminals or the UTC system, clock synchronization is performed according to the following principle: when a terminal of a low synchronization level receives a synchronization signal of a high synchronization level, clock synchronization is performed according to the received synchronization signal of the high synchronization level, for example, a receiving clock of the synchronization signal of the high synchronization level is used as a transmitting clock of the terminal. Preferably, the timing compensation based on the distance calibration or the uplink synchronization calibration may be performed on the received high-synchronization-level synchronization signal, and a receiving clock of the high-synchronization-level synchronization signal after the timing compensation is used as the transmitting clock of the terminal.

For example, if the terminal receives the downlink pilot signal transmitted by the base station of synchronization level 0 and receives the synchronization signal transmitted by the terminal of synchronization level 1 when the terminal cannot receive the time service signal of the UTC system, the terminal preferentially performs clock synchronization with the base station of synchronization level 0 as a synchronization source to enter synchronization level 2. Further, if the clock synchronization with the base station of the synchronization level 0 is not possible, the clock synchronization is performed by using the terminal of the synchronization level 1 as the synchronization source.

For clarity, fig. 1 shows a flow of one implementation of a first clock synchronization scheme. Generally speaking, in the first clock synchronization scheme described in the process, if a terminal receives a time service signal of a UTC system, the UTC system is used as a synchronization source to perform clock synchronization, and a synchronization level 1 is entered; otherwise, if the synchronization signal is received within the first time period, performing clock synchronization by using the terminal or the base station which sends the synchronization signal as a synchronization source according to the level of the synchronization signal.

Specifically, as shown in fig. 1, in step 101, when the terminal is powered on and then starts the timer d1, the counting time of the timer d1 is t1 (i.e., the first time).

During the timing time of the timer d1, the following steps can be performed according to the receiving situation of the synchronization signal:

if a time service signal of the UTC system is received, performing clock synchronization by using the UTC system as a synchronization source, and entering a synchronization level 1 (see steps 102-103);

otherwise, if receiving a downlink pilot signal sent by the base station of synchronization level 0, if TC is 1 (that is, timing compensation is not enabled), the terminal performs clock synchronization with the base station of synchronization level 0 as a synchronization source, and enters synchronization level 2; when TC is 0 (that is, timing compensation is enabled), if the terminal performs clock synchronization based on the timing compensation with the base station as a synchronization source, the terminal enters the synchronization level 3, and if the terminal performs clock synchronization with the base station as a synchronization source but the clock synchronization is not based on the timing compensation, the terminal enters the synchronization level 3 (see steps 104 to 107);

otherwise, if receiving the synchronization signal sent by the terminal of the synchronization level 1, performing clock synchronization by using the terminal of the synchronization level 1 as a synchronization source, and entering the synchronization level 2 (see step 108 to step 109);

otherwise, if receiving the synchronization signal sent by the terminal of the synchronization level 2, performing clock synchronization by using the terminal of the synchronization level 2 as a synchronization source, and entering the synchronization level 3 (see step 110 to step 111);

otherwise, if receiving the downlink pilot signal sent by the base station of the synchronization level 3, performing clock synchronization by using the base station of the synchronization level 3 as a synchronization source, and entering the synchronization level 3 (see step 112 to step 113);

otherwise, if receiving the synchronization signal sent by the terminal of the synchronization level 3, performing self-synchronization according to the terminal of the synchronization level 3, and entering the synchronization level 3 (see steps 114 to 115);

otherwise, if the timer d1 times out, the timer d2 is started after the timer d1 times out, and the synchronization level 3 is entered after the timer d2 times out (see steps 116-117).

It should be noted that, the terminal of synchronization level 3 and the base station of synchronization level 3 may be considered to have the same synchronization level, and thus steps 112 to 115 in the above flow may also be described as: if the terminal receives the synchronization signal of synchronization level 3, the terminal performs clock synchronization in a self-synchronization manner and enters synchronization level 3 regardless of whether the synchronization signal of synchronization level 3 is from the base station or from another terminal.

As can be seen from the description of the first clock synchronization scheme, if the terminal receives the time service signal of the UTC system, the UTC system is used as a synchronization source to perform clock synchronization, and the UTC system enters a synchronization level 1; otherwise, if the synchronous signal is received within the first time period, performing clock synchronization by using the terminal or the base station which sends the synchronous signal as a synchronous source according to the grade of the synchronous signal. It can be seen that, according to different situations, the terminal can enter different synchronization levels to achieve clock synchronization with different accuracies.

(II) clock synchronization scheme II

In the second clock synchronization scheme, 5 synchronization levels are defined, and the 5 synchronization levels are respectively called as: sync level 0, sync level 1a, sync level 1, sync level 2, and sync level 3. Wherein, the synchronization level 0 may be base station specific, and the synchronization level 1a, the synchronization level 1, the synchronization level 2, and the synchronization level 3 may be terminal specific. Generally, the higher the synchronization level, the higher the synchronization accuracy.

It should be noted that the naming manner of the above 5 synchronization levels is only an example, and the embodiment of the present invention also allows other naming manners to be adopted, such as that the above synchronization level 1 is referred to as a first synchronization level, the above synchronization level 2 is referred to as a second synchronization level, and so on, which are not listed here.

It should be noted that, in the synchronization levels defined in the second clock synchronization scheme, the names of some synchronization levels are the same as those of the synchronization levels defined in the first clock synchronization scheme, but the meanings of the synchronization levels should be interpreted based on the definitions in the corresponding clock synchronization schemes.

(1) Synchronization level 0

The synchronization level of the base station is configured as synchronization level 0 by default.

(2) Synchronization level 1a

If the terminal can receive the downlink pilot signal sent by the base station with the synchronization level 0 and performs clock synchronization with the base station as a synchronization source, the synchronization level of the terminal is synchronization level 1 a.

(3) Synchronization level 1

In one scenario, if a terminal cannot receive a downlink pilot signal transmitted by a base station of synchronization level 0, but receives a synchronization signal transmitted by a terminal of synchronization level 1a, and performs clock synchronization with the terminal of synchronization level 1a as a synchronization source, the synchronization level of the terminal is synchronization level 1.

In another scenario, if the terminal does not receive the synchronization signal sent by the terminal with the synchronization level 1a, but receives the time service signal of the UTC system, and performs clock synchronization with the UTC system as a synchronization source, the synchronization level of the terminal is synchronization level 1.

(4) Synchronization level 2

If the terminal receives only the synchronization signal sent by the terminal with the synchronization level not higher than 1 (the terminal with the synchronization level not higher than 1 includes the terminal with the synchronization level 1), for example, the terminal does not receive the synchronization signal sent by the terminal with the synchronization level 1a, but receives the synchronization signal sent by the terminal with the synchronization level 1, and the terminal performs clock synchronization with the terminal with the synchronization level 1 as a synchronization source, the synchronization level of the terminal is synchronization level 2.

(5) Synchronization level 3

In one scenario, if a terminal receives a synchronization signal transmitted by a terminal of a synchronization level 1a and performs clock synchronization with the terminal of the synchronization level 1a as a synchronization source, the synchronization level of the terminal is a synchronization level 3.

In another scenario, if a terminal receives only a synchronization signal sent by a terminal with a synchronization level not higher than 2 (the terminal with the synchronization level not higher than 2 includes a terminal with a synchronization level 2), for example, the terminal does not receive a synchronization signal sent by a terminal with a synchronization level 1a or a synchronization level 1, but receives a synchronization signal sent by a terminal with a synchronization level 2, and performs clock synchronization with the terminal with the synchronization level 2 as a synchronization source, the synchronization level of the terminal is synchronization level 3.

In another scenario, if the terminal receives only the synchronization signal sent by the terminal of synchronization level 3, the terminal performs self-synchronization according to the synchronization signal of synchronization level 3 received in N (N is an integer greater than or equal to 1) synchronization periods, and enters synchronization level 3. The specific implementation of the self-synchronization is consistent with the foregoing embodiments, and is not described in detail here.

In the second clock synchronization scheme, if the terminal can receive the synchronization signal sent by the base station or other terminals or the UTC system, the clock synchronization is performed according to the following principle: when a terminal of a low synchronization level receives a synchronization signal of a high synchronization level, clock synchronization is performed according to the received synchronization signal of the high synchronization level, for example, a receiving clock of the synchronization signal of the high synchronization level is used as a transmitting clock of the terminal. Preferably, the timing compensation based on the distance calibration or the uplink synchronization calibration may be performed on the received high-synchronization-level synchronization signal, and a receiving clock of the high-synchronization-level synchronization signal after the timing compensation is used as the transmitting clock of the terminal.

For clarity, fig. 2 shows a flow of one implementation of the second clock synchronization scheme. In the second clock synchronization scheme described in the process, if the terminal receives the downlink pilot signal sent by the base station of synchronization level 0, the base station of synchronization level 0 is used as a synchronization source to perform clock synchronization, and the terminal enters synchronization level 1 a; otherwise, if receiving the synchronization signal sent by other terminals or the time service signal of the UTC system within the first time period, performing clock synchronization by using the other terminals as synchronization sources or using the UTC system as a synchronization source according to the synchronization levels of the other terminals.

Specifically, as shown in fig. 2, in step 201, when the terminal starts up, the timer d1 is started, and the counting time length of the timer d1 is t1 (i.e., the first time length mentioned above). It should be noted that the definition of the timer d1 and the first duration is limited to the clock synchronization scheme two.

if receiving a downlink pilot signal sent by a base station of a synchronization level 0, performing clock synchronization by using the base station as a synchronization source, and entering a synchronization level 1a (see steps 202 to 203);

otherwise, if receiving the synchronization signal sent by the terminal of the synchronization level 1a, performing clock synchronization by using the terminal of the synchronization level 1a as a synchronization source, and entering the synchronization level 3 (see step 204-step 205);

otherwise, if receiving the time service signal sent by the UTC system, performing clock synchronization by using the UTC system as a synchronization source, and entering a synchronization level 1 (see step 206-step 207);

otherwise, if receiving the synchronization signal sent by the terminal of the synchronization level 1, performing clock synchronization by using the terminal of the synchronization level 1 as a synchronization source, and entering the synchronization level 2 (see step 208-step 209);

otherwise, if receiving the synchronization signal sent by the terminal of the synchronization level 2, performing clock synchronization by using the terminal of the synchronization level 2 as a synchronization source, and entering the synchronization level 3 (see step 210-step 211);

otherwise, if receiving the synchronization signal sent by the terminal of the synchronization level 3, performing self-synchronization according to the terminal of the synchronization level 3, and entering the synchronization level 3 (see step 212 to step 213);

otherwise, if the timer d1 times out, the timer d2 is started after the timer d1 times out, and the synchronization level 3 is entered after the timer d2 times out (see step 214-step 215).

As can be seen from the description of the second clock synchronization scheme, if the terminal receives the downlink pilot signal sent by the base station of the synchronization level 0, the base station of the synchronization level 0 is used as a synchronization source to perform clock synchronization, and the terminal enters the synchronization level 1 a; otherwise, if the synchronization signal sent by other terminals or the time service signal of the UTC system is received in the first time period, the other terminals or the UTC system is used as a synchronization source to carry out clock synchronization. It can be seen that, according to different situations, the terminal can enter different synchronization levels to achieve clock synchronization with different accuracies.

General scheme for (III) synchronous information transmission

Referring to fig. 3, a schematic diagram of a synchronization information transmission process provided in an embodiment of the present invention includes:

step 301: a terminal acquires a synchronous signal sequence to be sent; if the terminal receives the broadcast message sent by the base station, the synchronous signal sequence is obtained according to the broadcast message, otherwise, the synchronous signal sequence is obtained from a preset synchronous signal sequence set according to the synchronization level of the terminal.

In this embodiment, a synchronization signal sequence set may be configured in advance on the base station side and the terminal side, and the set includes a plurality of synchronization signal sequences. The set may include N subsets (N being an integer greater than or equal to 3), with different synchronization levels corresponding to different subsets. Thus, at the base station side, the base station notifies the terminal of the synchronization signal sequences required to be sent by the terminals of different levels through broadcast messages according to different synchronization levels; on the terminal side, if the terminal cannot receive the broadcast message sent by the base station, that is, cannot acquire the synchronization signal sequence notified by the base station through the broadcast message, the synchronization signal sequence that the terminal needs to send may be acquired from the corresponding subset in the synchronization signal sequence set according to the synchronization level of the terminal itself.

Step 302: and the terminal determines a synchronous subframe for sending the synchronous information according to the synchronous grade of the terminal.

In this embodiment, a synchronization period may be predefined to include 2 or more than 2 synchronization subframes, and a synchronization level corresponding to each synchronization subframe is defined, one synchronization subframe may correspond to one or more synchronization levels, and synchronization levels or synchronization level combinations corresponding to different synchronization subframes are different from each other. Therefore, the terminal can determine the synchronous subframe for sending the synchronous information according to the own synchronous grade, so that the synchronous subframes used by the terminals with different synchronous grades for sending the synchronous information are orthogonal as much as possible in the time domain, and the synchronous resource conflict among the terminals with different synchronous grades is reduced or avoided.

Step 303: and the terminal sends the synchronization information in the determined synchronization subframe, wherein the sent synchronization information comprises the acquired synchronization signal sequence. Further, the synchronization information transmitted by the terminal may further include content of a Physical Broadcast Channel (PBSCH).

The terminal can use the synchronization signal and the PBSCH to perform time and frequency estimation and can further be used for demodulation of data. The PBSCH may be used to convey some system-level information, such as DFN (D2D Frame Number ), synchronization status, setup information (e.g., channel bandwidth, etc.).

Specifically, the content contained in the PBSCH may include:

14bits ═ 10 bits counter + 4bits offset (consistent with the DFN of the clock source);

TDD UL-DL config (TDD uplink and downlink configuration): 3 bits; for FDD systems, these 3bits are set to 000;

a GNSS enable bit G (in-coverage indicator bit): 1bit, in the pre-configuration, G ═ 0; the value G may be 0 or 1, where a value 1 indicates that the terminal is an in-coverage terminal, and a value 0 indicates that the terminal is not an in-coverage terminal, may be a partial coverage terminal, and may be an out-coverage terminal;

-system bandwidth 3 bits;

reserved field 20bits, whose content is derived from SIB (System Information Block) signaling or whose content is a pre-configured value.

The above process is applicable to the first clock synchronization scheme or the second clock synchronization scheme. If the first clock synchronization scheme is applied, the definition of the synchronization level involved in the process can be explained according to the definition of the synchronization level in the first clock synchronization scheme; if the second clock synchronization scheme is applied, the definition of the synchronization level involved in the process can be explained according to the definition of the synchronization level in the second clock synchronization scheme.

The process may also be independent of the first clock synchronization scheme and independent of the second clock synchronization scheme, in which case the definition of the synchronization level involved in the process can be interpreted according to the definition of the relevant synchronization level in the clock synchronization scheme to which the process applies.

In order to more clearly understand the above synchronization information transmission scheme, the following description will take the scenario of the above clock synchronization scheme one and the scenario of the above clock synchronization scheme two as examples, respectively, to describe in detail.

Synchronous information transmission scheme under (IV) clock synchronization scheme

In a scenario of the first clock synchronization scheme, the following situations may be specifically included:

scene 1: the terminal cannot receive the broadcast message of the base station, such as a V2V (Vehicle to Vehicle) message;

scene 2: the terminal may receive the broadcast message of the base station.

The following describes the transmission schemes of the synchronization information in the above two scenarios.

(1) Scene 1: the terminal cannot receive the broadcast message of the base station

In some embodiments, a set of Synchronization Signal (such as SLSS (side Link Synchronization Signal, D2D Synchronization Signal)) sequences may be divided into 3 subsets: SLSS subset 1, SLSS subset 2, SLSS subset 3. Wherein, the number of SLSS sequences contained in the SLSS subset 3 is not less than the number of SLSS sequences contained in the SLSS subset 2. These 3 subsets correspond to synchronization level 1, synchronization level 2, and synchronization level 3, respectively. In this case, the terminal determines the synchronization signal sequence to be transmitted according to the following principle:

the terminal in synchronization level 1 selects a specific SLSS sequence from SLSS subset 1, for example, the terminal in synchronization level 1 may pre-agree to select an SLSS sequence with an index number of SLSS10 from SLSS subset 1 (each SLSS sequence in SLSS subset 1 is identified by a unique index number);

the terminal at synchronization level 2 selects a specific SLSS sequence from SLSS subset 2, for example, the terminal at synchronization level 2 may pre-agree to select an SLSS sequence with an index number of SLSS20 from SLSS subset 2 (each SLSS sequence in SLSS subset 2 is identified by a unique index number);

a terminal of sync level 3 may comprise two cases:

i) if the terminal of synchronization level 3 enters synchronization level 3 without clock synchronization with any synchronization source, the terminal selects an SLSS sequence from SLSS subset 3, for example, selects an SLSS sequence from SLSS subset 3 randomly;

ii) if the terminal of the synchronization level 3 is clock-synchronized with the synchronization source of which the synchronization level is not lower than the synchronization level 3 to enter the synchronization level 3, the terminal acquires a synchronization signal sequence identical to or corresponding to the synchronization signal sequence transmitted by the synchronization source according to the synchronization source. For example, if the terminal a performs clock synchronization with the terminal B of the synchronization level 3 as a synchronization source to enter the synchronization level 3, the terminal a takes the SLSS sequence sent by the terminal B as the SLSS sequence that the terminal a needs to send; if the terminal A uses the terminal C with the synchronization level of 2 as a synchronization source to perform clock synchronization and enter the synchronization level 3, the terminal A selects an SSLS sequence corresponding to the SSLS sequence from the SLSS subset 3 as the SSLS sequence which needs to be sent by the terminal A according to the SSLS sequence sent by the terminal C. As an example, if the index number of the SSLS sequence sent by the terminal C in the SSLS subset 2 is SSLS2n, the terminal a selects the SSLS sequence with the same index number from the SLSS subset 3.

Under the same scenario, in other embodiments, the SLSS sequence set may be divided into 2 subsets: SLSS subset 1, SLSS subset 2, SLSS subset 1 is further divided into subset 1a and subset 1 b. Wherein, the number of SLSS sequences contained in the subset 2 is not less than the number of SLSS sequences in the subset 1. Subset 1a corresponds to sync level 1, subset 1b corresponds to sync level 2, and SSLS subset 2 corresponds to sync level 3. In this case, the principle according to which the terminal determines the synchronization signal sequence to be transmitted is as described above, and is not repeated here, but because the synchronization level is different from the corresponding relationship of the subset in the SLSS sequence set, the SLSS sequence needs to be selected from the corresponding subset according to the corresponding relationship agreed in this case in the specific implementation.

In this embodiment, in a synchronization period, 3 subframes are reserved as synchronization subframes, where the synchronization subframes may transmit synchronization information (including synchronization pilots and broadcast messages, for example), and the 3 synchronization subframes may be continuous or discontinuous in a time domain. Generally, one synchronization period is 40ms, and the length of the synchronization period is not limited by the embodiment of the present invention.

These 3 synchronization subframes can be represented as: a first synchronization subframe, a second synchronization subframe, and a third synchronization subframe. Here, "the first synchronization subframe" does not mean "the first synchronization subframe", and it may be any one of the 3 synchronization subframes, and the "first", "second", and "third" are used only for distinguishing the synchronization subframes and do not represent other meanings.

As an example, it may be agreed that the first synchronization subframe corresponds to synchronization class 1 and synchronization class 3, the second synchronization subframe corresponds to synchronization class 2, and the third synchronization subframe corresponds to synchronization class 3. In this way, the terminal may determine the synchronization subframe used for sending the synchronization information according to the synchronization level of the terminal itself, which may specifically include the following cases:

-if the synchronization level of the terminal is synchronization level 1, determining a first synchronization subframe as a synchronization subframe for transmitting synchronization information;

-if the synchronization level of the terminal is synchronization level 2, determining a second synchronization subframe as the synchronization subframe for transmitting synchronization information;

-if the terminal has a synchronization level of 3 and is able to receive a synchronization signal transmitted by a terminal of synchronization level 2, determining a third synchronization subframe as the synchronization subframe for transmitting synchronization information; otherwise, the first synchronization subframe or the third synchronization subframe is determined as the synchronization subframe for transmitting the synchronization information (e.g., one synchronization subframe is randomly selected from the first synchronization subframe and the third synchronization subframe).

In other embodiments, within one synchronization period, 2 subframes are reserved as synchronization subframes, which may transmit synchronization information (e.g., including synchronization pilot and broadcast message), and the 2 synchronization subframes may be continuous or discontinuous in the time domain. Generally, one synchronization period is 40ms, and the length of the synchronization period is not limited by the embodiment of the present invention.

These 2 synchronization subframes can be represented as: a first synchronization subframe and a second synchronization subframe. Here, "the first synchronization subframe" does not mean "the first synchronization subframe", and it may be any one of the 2 synchronization subframes, and the "first" and "second" are used only for distinguishing the synchronization subframes and do not represent other meanings.

As an example, it may be agreed that the first synchronization subframe corresponds to synchronization level 1 and synchronization level 3, and the second synchronization subframe corresponds to synchronization level 2 and synchronization level 3. In this way, the terminal may determine the synchronization subframe used for sending the synchronization information according to the synchronization level of the terminal itself, which may specifically include the following cases:

-if the terminal has a synchronization level of 3 and is able to receive a synchronization signal transmitted by a terminal of synchronization level 2, determining a first synchronization subframe as a synchronization subframe for transmitting synchronization information; otherwise, the first synchronization subframe or the second synchronization subframe is determined as the synchronization subframe for transmitting the synchronization information (e.g., one synchronization subframe is randomly selected from the first synchronization subframe and the second synchronization subframe).

In other embodiments, within one synchronization period, 2 subframes are reserved as synchronization subframes, which may transmit synchronization information (e.g., including synchronization pilot and broadcast message), and the 2 synchronization subframes may be continuous or discontinuous in the time domain. Generally, one synchronization period is 40ms, and the length of the synchronization period is not limited by the embodiment of the present invention. These 2 synchronization subframes can be represented as: a first synchronization subframe and a second synchronization subframe. Here, "the first synchronization subframe" does not mean "the first synchronization subframe", and it may be any one of the 2 synchronization subframes, and the "first" and "second" are used only for distinguishing the synchronization subframes and do not represent other meanings.

As an example, it may be agreed that the first synchronization subframe corresponds to synchronization level 1 and the second synchronization subframe corresponds to synchronization level 2. In this way, the terminals of synchronization level 1 and synchronization level 2 can determine the synchronization sub-frame they use to transmit synchronization information according to their own synchronization levels. However, for the terminal of synchronization level 3, the synchronization subframe for transmitting the synchronization information cannot be determined, and thus the transmission of the synchronization information is abandoned.

Further, the terminals of synchronization level 1, synchronization level 2, and synchronization level 3 may use different frequency domain resources to transmit synchronization information. Fig. 4 is a diagram illustrating exemplary frequency domain resources occupied by synchronization information.

Further, if the synchronization information transmitted by the terminal also includes PBSCH content, the terminal may acquire the predefined PBSCH content and transmit the predefined PBSCH content together with the SLSS sequence in the synchronization subframe when the terminal cannot receive the broadcast message transmitted by the base station.

(2) Scene 2: the terminal can receive the broadcast message of the base station

In some embodiments, the set of synchronization signal (e.g., SLSS) sequences may be divided into 3 subsets in the manner previously described: SLSS subset 1, SLSS subset 2, SLSS subset 3. These 3 subsets correspond to synchronization level 1, synchronization level 2, and synchronization level 3, respectively. In this case, the broadcast message sent by the base station may carry indication information of synchronization signal sequences corresponding to various synchronization levels, which may specifically include the following cases:

the SLSS sequence corresponding to the synchronization level 1 is selected from the SLSS subset 1, for example, an SLSS sequence with an index number of SLSS10 can be pre-agreed to be selected from the SLSS subset 1 for the synchronization level 1 (each SLSS sequence in the SLSS subset 1 is identified by a unique index number);

the SLSS sequence corresponding to the synchronization level 2 is selected from the SLSS subset 2, for example, an SLSS sequence with an index number of SLSS20 can be pre-agreed to be selected from the SLSS subset 2 for the synchronization level 2 (each SLSS sequence in the SLSS subset 2 is identified by a unique index number);

the SLSS sequence corresponding to the synchronization level 3 is selected from the SLSS subset 3, for example, the terminal of the synchronization level 3 may pre-agree to select the SLSS sequence with the index number SLSS30 from the SLSS subset 3 (each SLSS sequence in the SLSS subset 3 is identified by a unique index number).

In other embodiments, the SLSS sequence set may be divided into 2 subsets in the manner described above: SLSS subset 1, SLSS subset 2, SLSS subset 1 is further divided into subset 1a and subset 1 b. Subset 1a corresponds to sync level 1, subset 1b corresponds to sync level 2, and SSLS subset 2 corresponds to sync level 3. In this case, the principle according to which the base station notifies the synchronization signal sequences of the synchronization levels through the broadcast message is as described above, and is not repeated here, but the correspondence between the synchronization levels and the subsets in the SLSS sequence set is different, and in the specific implementation, the SLSS sequence needs to be selected from the corresponding subset according to the correspondence agreed in such a case.

As described in the above scenario 1, 2 or 3 synchronization subframes may be configured in one synchronization period, and a process of determining, by a terminal, a synchronization subframe in which the terminal transmits synchronization information according to its own synchronization level may be described in the above scenario 1, and is not repeated here.

Further, if the synchronization information sent by the terminal also includes PBSCH content, the terminal may acquire the PBSCH content according to the broadcast message and send the acquired PBSCH content together with the SLSS sequence in the synchronization subframe, if the terminal can receive the broadcast message sent by the base station. Wherein, the base station can carry the PBSCH content or the related information in the broadcast message.

Synchronous information transmission scheme under clock synchronization scheme two

In the second scenario of the clock synchronization scheme, the following situations may be specifically included:

scene 3: the terminal cannot receive the broadcast message of the base station, such as the V2V message, and cannot receive the synchronization signal sent by the terminal of synchronization level 1 a;

scene 4: the terminal can not receive the broadcast message of the base station, but can receive the synchronous signal sent by the terminal with the synchronous level 1 a;

scene 5: the terminal can receive the broadcast message transmitted by the base station.

(1) Scene 3: the terminal can not receive the broadcast message of the base station and can not receive the synchronous signal transmitted by the terminal with the synchronous level 1a

In this scenario, the set of synchronization signal (e.g., SLSS) sequences can be divided into 3 subsets: SLSS subset 1, SLSS subset 2, SLSS subset 3. For a specific division method and a corresponding relationship between each subset and the synchronization level, see the related description in scenario 1. Accordingly, the principle of the terminal determining the synchronization signal sequence to be transmitted can also be referred to the correlation description in scenario 1.

In this scenario, one synchronization period may include 2 or 3 synchronization subframes. The corresponding relationship between each synchronization subframe and the synchronization level, and the manner in which the terminal determines the synchronization subframe for sending the synchronization information, can be referred to the related description in scenario 1.

Preferably, the synchronization level 1a and the synchronization level 1 correspond to the same synchronization subframe. If the synchronization level of the terminal is synchronization level 3 and the terminal of synchronization level 1a is used as a synchronization source to perform clock synchronization to enter synchronization level 3, selecting a second synchronization signal sequence from a subset corresponding to the synchronization level 3 according to a first synchronization signal sequence sent by the terminal of synchronization level 1a used as the synchronization source, and then sending the second synchronization signal sequence in a synchronization subframe behind the synchronization subframe occupied by the synchronization signal of synchronization level 1 a.

Further, if the synchronization information transmitted by the terminal further includes the PBSCH content, the terminal may acquire the predefined PBSCH content and transmit the predefined PBSCH content together with the SLSS sequence in the synchronization subframe when the terminal cannot receive the broadcast message transmitted by the base station and cannot receive the synchronization signal transmitted by the terminal of synchronization level 1 a.

(2) Scene 4: the terminal can not receive the broadcast message of the base station, but can receive the synchronous signal transmitted by the terminal with the synchronous level 1a

Specifically, if the synchronization level of the terminal is 3, and the terminal of the synchronization level 1a is used as a synchronization source to perform clock synchronization to enter the synchronization level 3, selecting a second synchronization signal sequence from a subset corresponding to the synchronization level 3 according to a first synchronization signal sequence sent by the terminal of the synchronization level 1a as the synchronization source; the corresponding relation between the first synchronization signal sequence and the second synchronization signal sequence is predetermined.

In this scenario, one synchronization period may include 2 or 3 synchronization subframes. The corresponding relationship between each synchronization subframe and the synchronization level, and the manner in which the terminal determines the synchronization subframe for sending the synchronization information, can be referred to the related description in scenario 1. Preferably, the synchronization level 1a and the synchronization level 1 correspond to the same synchronization subframe. If the synchronization level of the terminal is synchronization level 3 and the terminal of synchronization level 1a is used as a synchronization source to perform clock synchronization to enter synchronization level 3, selecting a second synchronization signal sequence from a subset corresponding to the synchronization level 3 according to a first synchronization signal sequence sent by the terminal of synchronization level 1a used as the synchronization source, and then sending the second synchronization signal sequence in a synchronization subframe behind the synchronization subframe occupied by the synchronization signal of synchronization level 1 a.

Furthermore, if the synchronization information transmitted by the terminal also includes the PBSCH content, if the terminal cannot receive the broadcast message transmitted by the base station but can receive the synchronization signal transmitted by the terminal of synchronization level 1a, the terminal can acquire the PBSCH content from the synchronization information transmitted by the terminal of synchronization level 1a and transmit the acquired PBSCH content together with the SLSS sequence in the synchronization subframe.

(3) Scene 5: the terminal can receive the broadcast message sent by the base station

In this scenario, the set of synchronization signal (e.g., SLSS) sequences can be divided into 3 subsets: SLSS subset 1, SLSS subset 2, SLSS subset 3. For a specific division method and a corresponding relationship between each subset and the synchronization level, see the related description in scenario 1. Accordingly, the manner in which the base station notifies the synchronization signal sequence corresponding to each synchronization level through the broadcast message can also be referred to as the related description in scenario 1.

In particular, for synchronization level 1, the base station may select 1 SLSS sequence from SLSS subset 1 and notify through a broadcast message.

Further, if the terminal detects that the synchronization signaling sent by the synchronization source is from the SLSS sequence in SLSS subset 1, and G in the PBSCH is 1, it may determine that the synchronization level of the synchronization source is synchronization level 1 a.

Based on the same technical concept, as shown in fig. 5 and fig. 6, embodiments of the present invention further provide a terminal, which can implement the first clock synchronization scheme.

The terminal shown in fig. 5 may include: a receiving module 501 and a synchronization module 502. A synchronization module 502, configured to perform clock synchronization using the UTC system as a synchronization source if the receiving module 501 receives a time service signal of the UTC system, and enter a synchronization level 1; otherwise, if the receiving module receives the synchronous signal within the first time length, the terminal or the base station which sends the synchronous signal is used as a synchronous source to carry out clock synchronization according to the grade of the synchronous signal.

Preferably, the synchronization module 502 may be specifically configured to:

if the receiving module 501 receives a synchronization signal sent by a terminal of a synchronization level 1 within a first time period, performing clock synchronization by using the terminal of the synchronization level 1 as a synchronization source, and entering a synchronization level 2; or,

if the receiving module 501 does not receive the synchronization signal sent by the terminal of the synchronization level 1 but receives the synchronization signal sent by the terminal of the synchronization level 2 within the first time period, performing clock synchronization by using the terminal of the synchronization level 2 as a synchronization source, and entering the synchronization level 3; or,

if the receiving module 501 only receives the synchronization signal sent by the synchronization level 3 within the first time period, performing clock synchronization according to all the synchronization signals of the synchronization level 3 received in N synchronization periods, or performing clock synchronization by using a terminal in the front time from among source terminals of the synchronization signals of the synchronization level 3 received in the N synchronization periods as a synchronization source, and entering the synchronization level 3, where N is an integer greater than or equal to 1; the synchronization signal of synchronization level 3 includes a synchronization signal sent by a terminal and/or a base station of synchronization level 3, and the base station of synchronization level 3 refers to: a base station that is not clock-synchronized with the UTC system or a base station that cannot obtain its own position.

Preferably, the synchronization module 502 may be further configured to: if the receiving module 501 does not receive the time service signal of the UTC system within the first time period, and also does not receive the synchronization signal sent by the base station or other terminals, when a second time period after the first time period expires, the synchronization level 3 is entered.

Preferably, the synchronization module 502 is further operable to: if the receiving module 501 of the terminal entering the synchronization level 1 receives the synchronization signal sent by the base station or other terminals, the base station or other terminals sending the synchronization signal is abandoned as the synchronization source to perform clock synchronization.

The terminal shown in fig. 6 may include: a processor 601, a memory 602, a transceiver 603, and a bus interface.

The processor 601 is responsible for managing the bus architecture and general processing, and the memory 602 may store data used by the processor 601 in performing operations. The transceiver 603 is used for receiving and transmitting data under the control of the processor 601.

The bus architecture may include any number of interconnected buses and bridges, with one or more processors, represented by processor 601, and various circuits of memory, represented by memory 602, being linked together. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. The bus interface provides an interface. The transceiver 603 may be a number of elements, including a transmitter and a transceiver, providing a means for communicating with various other apparatus over a transmission medium. The processor 601 is responsible for managing the bus architecture and general processing, and the memory 602 may store data used by the processor 601 in performing operations.

The first clock synchronization scheme disclosed in the embodiment of the present invention may be applied to the processor 601, or implemented by the processor 601. In implementation, the steps of a flow of the clock synchronization scheme may be performed by integrated logic circuits of hardware or instructions in the form of software in the processor 601. The processor 601 may be a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the like that implement or perform the methods, steps, and logic blocks disclosed in embodiments of the present invention. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of a method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware processor, or may be implemented by a combination of hardware and software modules in the processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in the memory 602, and the processor 601 reads the information in the memory 602 and completes the steps of the process of the first clock synchronization scheme provided in the foregoing embodiment in combination with the hardware thereof.

Specifically, the processor 601, configured to read the program in the memory 602, executes the process of the first clock synchronization scheme described in the foregoing embodiments. For a specific implementation of the process, reference may be made to the foregoing embodiments, which are not described herein again.

Based on the same technical concept, as shown in fig. 7 and fig. 8, embodiments of the present invention further provide a terminal, respectively, where the terminal can implement the second clock synchronization scheme.

The terminal as shown in fig. 7 may include: a receiving module 701 and a synchronization module 702; a synchronization module 702, configured to perform clock synchronization using the base station of synchronization level 0 as a synchronization source if the receiving module 701 receives a downlink pilot signal sent by the base station of synchronization level 0, and enter synchronization level 1 a; otherwise, if the receiving module receives a synchronization signal sent by other terminals or a time service signal of the UTC system within the first time length, the other terminals are used as synchronization sources or the UTC system is used as a synchronization source to perform clock synchronization according to the synchronization levels of the other terminals.

Preferably, the synchronization module 702 may be specifically configured to:

if the receiving module 701 receives only a synchronization signal sent by a terminal with a synchronization level not higher than 1 in a first time period, and the terminal with the synchronization level not higher than 1 includes a terminal with a synchronization level 1, performing clock synchronization by using the terminal with the synchronization level 1 as a synchronization source, and entering a synchronization level 2; or,

if the receiving module 701 receives only a synchronization signal sent by a terminal with a synchronization level not higher than 2 in a first time period, and the terminal with the synchronization level not higher than 2 includes a terminal with a synchronization level 2, performing clock synchronization by using the terminal with the synchronization level 2 as a synchronization source, and entering a synchronization level 3; or,

if the receiving module 701 only receives the synchronization signal sent by the terminal of the synchronization level 3 within the first time period, performing clock synchronization according to all the synchronization signals of the synchronization level 3 received in N synchronization periods, or performing clock synchronization by using a terminal in the front time of the source terminal of the synchronization signal of the synchronization level 3 received in the N synchronization periods as a synchronization source, and entering the synchronization level 3, where N is an integer greater than or equal to 1.

Preferably, the synchronization module 702 may be specifically configured to: if the receiving module 701 does not receive the synchronization signal sent by the terminal of the synchronization level 1a within the first time period, but receives the time service signal of the UTC system, the UTC system is used as a synchronization source to perform clock synchronization, and the UTC system enters the synchronization level 1.

Preferably, the synchronization module 702 is further operable to: if the receiving module 701 does not receive the synchronization signal sent by the base station or other terminals within the first time period, then when a second time period after the first time period expires, the synchronization level 3 is entered.

The terminal shown in fig. 8 may include: a processor 801, a memory 802, a transceiver 803, and a bus interface.

The processor 801 is responsible for managing the bus architecture and general processing, and the memory 802 may store data used by the processor 801 in performing operations. The transceiver 803 is used for receiving and transmitting data under the control of the processor 801.

The bus architecture may include any number of interconnected buses and bridges, with one or more processors, represented by the processor 801, and various circuits, represented by the memory 802, being linked together. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. The bus interface provides an interface. The transceiver 803 may be a plurality of elements, i.e., including a transmitter and a transceiver, providing a means for communicating with various other apparatus over a transmission medium. The processor 801 is responsible for managing the bus architecture and general processing, and the memory 802 may store data used by the processor 801 in performing operations.

The flow of the second clock synchronization scheme disclosed in the embodiment of the present invention may be applied to the processor 801, or implemented by the processor 801. In implementation, the steps of the second flow of the clock synchronization scheme may be implemented by hardware integrated logic circuits or instructions in software in the processor 801. The processor 801 may be a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the like that implement or perform the methods, steps, and logic blocks disclosed in embodiments of the present invention. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of a method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware processor, or may be implemented by a combination of hardware and software modules in the processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in the memory 802, and the processor 801 reads information in the memory 802, and completes the steps of the flow of the clock synchronization scheme two provided by the foregoing embodiment in combination with hardware thereof.

Specifically, the processor 801 is configured to read the program in the memory 802 and execute the flow of the second clock synchronization scheme described in the foregoing embodiment. For a specific implementation of the process, reference may be made to the foregoing embodiments, which are not described herein again.

Based on the same technical concept, as shown in fig. 9 and 10, embodiments of the present invention further provide a terminal, which can implement the above-mentioned synchronization information transmission scheme.

The terminal shown in fig. 9 may include:

an obtaining module 901, configured to obtain a synchronization signal sequence to be sent; if the terminal receives a broadcast message sent by a base station, acquiring a synchronous signal sequence according to the broadcast message, otherwise, acquiring the synchronous signal sequence from a preset synchronous signal sequence set according to the synchronization level of the terminal;

a determining module 902, configured to determine, according to the synchronization level of the terminal, a synchronization subframe for sending synchronization information;

a sending module 903, configured to send synchronization information in the determined synchronization subframe, where the sent synchronization information includes the obtained synchronization signal sequence.

Preferably, the preconfigured synchronization signal sequence set includes N subsets, where N is an integer greater than or equal to 3, and different synchronization levels correspond to different subsets. Correspondingly, the obtaining module 901 is specifically configured to:

The obtaining module 901 is specifically configured to:

The obtaining module 901 may be specifically configured to:

the determining module 902 may be specifically configured to: when the synchronization subframe for sending the synchronization information is determined, determining a synchronization subframe behind the synchronization subframe occupied by the synchronization signal of the synchronization level 1a as the synchronization subframe for sending the synchronization information by the terminal.

Preferably, one synchronization period includes 3 synchronization subframes including a first synchronization subframe, a second synchronization subframe and a third synchronization subframe, the first synchronization subframe corresponds to a synchronization level 1 and a synchronization level 3, the second synchronization subframe corresponds to a synchronization level 2, and the third synchronization subframe corresponds to a synchronization level 3; accordingly, the determining module 902 may be specifically configured to:

Preferably, one synchronization period includes 2 synchronization subframes including a first synchronization subframe and a second synchronization subframe, the first synchronization subframe corresponds to a synchronization level 1 and a synchronization level 3, and the second synchronization subframe corresponds to a synchronization level 2 and a synchronization level 3; accordingly, the determining module 902 may be specifically configured to:

Preferably, one synchronization period includes 2 synchronization subframes including a first synchronization subframe and a second synchronization subframe, the first synchronization subframe corresponds to a synchronization level 1, and the second synchronization subframe corresponds to a synchronization level 2; accordingly, the determining module 902 may be specifically configured to:

Preferably, the preset synchronization signal sequence set includes N subsets, where N is an integer greater than or equal to 3, and different synchronization levels correspond to different subsets; the broadcast message sent by the base station carries indication information of a synchronization signal sequence, wherein: the synchronization signal sequence corresponding to the synchronization level 1 or the synchronization level 1a is selected from the subset corresponding to the synchronization level 1; the synchronization signal sequence corresponding to the synchronization level 2 is selected from the subset corresponding to the synchronization level 2; the synchronization signal sequence corresponding to synchronization level 3 is selected from the subset corresponding to synchronization level 3.

Preferably, the number of subsets included in the preconfigured synchronization signal sequence set is 3, the 3 subsets respectively correspond to a synchronization level 1, a synchronization level 2, and a synchronization level 3, and the number of synchronization signal sequences in the subset corresponding to the synchronization level 3 is not less than the number of synchronization signal sequences in the subset corresponding to the synchronization level 2; or, the preconfigured synchronization signal sequence set includes a first subset and a second subset, the first subset includes 2 subsets respectively corresponding to the synchronization level 1 and the synchronization level 2, the second subset corresponds to the synchronization level 3, and the number of the synchronization signal sequences in the second subset is not less than the number of the synchronization signal sequences in the first subset.

Preferably, the synchronization information sent by the terminal further includes PBSCH content; the PBSCH content sent by the terminal is acquired from the broadcast message if the terminal receives the broadcast message sent by the base station, otherwise, the PBSCH content sent by the terminal is pre-configured; or, the synchronization information sent by the terminal further includes PBSCH content; the PBSCH content sent by the terminal is configured in advance if the terminal does not receive the broadcast message sent by the base station and does not receive the synchronization signal sent by the terminal of the synchronization level 1a, the PBSCH content sent by the terminal is acquired from the synchronization signal sent by the terminal of the synchronization level 1a if the terminal does not receive the broadcast message of the base station but receives the synchronization signal sent by the terminal of the synchronization level 1a, and the PBSCH content sent by the terminal is acquired from the broadcast message sent by the base station if the terminal receives the broadcast message sent by the base station.

Preferably, the determining module 902 is further operable to: and if the synchronization resource used by the terminal is detected to conflict with the synchronization resource used by other terminals, selecting a new idle subframe to send synchronization information.

The terminal shown in fig. 10 may include: a processor 1001, a memory 1002, a transceiver 1003, and a bus interface.

The processor 1001 is responsible for managing the bus architecture and general processing, and the memory 1002 may store data used by the processor 801 in performing operations. The transceiver 1003 is used for receiving and transmitting data under the control of the processor 1001.

The bus architecture may include any number of interconnected buses and bridges, with one or more processors, represented by the processor 1001, and various circuits, represented by the memory 1002, being linked together. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. The bus interface provides an interface. The transceiver 1003 may be a number of elements including a transmitter and a transceiver, providing a means for communicating with various other apparatus over a transmission medium. The processor 1001 is responsible for managing the bus architecture and general processing, and the memory 1002 may store data used by the processor 1001 in performing operations.

The flow of the synchronization information transmission scheme disclosed in the embodiment of the present invention may be applied to the processor 1001, or implemented by the processor 1001. In implementation, the steps of the synchronization information transmission scheme flow may be implemented by instructions in the form of hardware, integrated logic circuits, or software in the processor 1001. The processor 1001 may be a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the like that implement or perform the methods, steps, and logic blocks disclosed in embodiments of the present invention. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of a method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware processor, or may be implemented by a combination of hardware and software modules in the processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in the memory 1002, and the processor 1001 reads the information in the memory 1002 and completes the steps of the flow of the synchronization information transmission scheme provided by the foregoing embodiment in combination with the hardware thereof.

Specifically, the processor 1001, configured to read the program in the memory 1002, executes the flow of the synchronization information transmission scheme described in the foregoing embodiment. For a specific implementation of the process, reference may be made to the foregoing embodiments, which are not described herein again.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A method of clock synchronization, comprising:

if the terminal receives a time service signal of a universal coordinated time (UTC) system, performing clock synchronization by using the UTC system as a synchronization source, and entering a synchronization level 1;

otherwise, if the synchronous signal is received within the first time span, performing clock synchronization by taking the terminal or the base station which sends the synchronous signal as a synchronous source according to the grade of the synchronous signal;

if the time service signal of the UTC system is not received within the first time length, but the downlink pilot signal sent by the base station with the synchronization level of 0 is received, then:

taking the base station of the synchronization level 0 as a synchronization source to carry out clock synchronization, and entering a synchronization level 2 or a synchronization level 3 according to a timing compensation enabling mark configured by the base station, wherein the timing compensation enabling mark is used for indicating whether timing compensation is enabled or not; if the timing compensation is enabled and the terminal performs clock synchronization based on the timing compensation performed by the distance calibration or the uplink synchronization calibration, the terminal enters a synchronization level 2, otherwise, the terminal enters a synchronization level 3, and if the timing compensation is not enabled, the terminal enters the synchronization level 2;

2. The method of claim 1, wherein the clock synchronization of the terminal transmitting the synchronization signal as a synchronization source according to the level of the synchronization signal if the synchronization signal is received within the first time period comprises:

3. The method of claim 1, further comprising:

and if the time service signal of the UTC system is not received in the first time period and the synchronization signal sent by the base station or other terminals is not received, entering a synchronization level 3 when a second time period after the first time period is up.

4. The method of claim 1, further comprising:

and if the terminal entering the synchronization level 1 receives the synchronization signal sent by the base station or other terminals, giving up the clock synchronization by taking the base station or other terminals sending the synchronization signal as a synchronization source.

5. A method of clock synchronization, comprising:

if the terminal receives a downlink pilot signal sent by a base station of a synchronization level 0, performing clock synchronization by using the base station of the synchronization level 0 as a synchronization source, and entering a synchronization level 1 a;

otherwise, if receiving a synchronization signal sent by other terminals or a time service signal of a universal coordinated time (UTC) system within a first time period, performing clock synchronization by using the other terminals as synchronization sources or using the UTC system as a synchronization source according to the synchronization levels of the other terminals;

if a synchronization signal sent by a terminal of a synchronization level 1a is received within a first time period, performing clock synchronization by using the terminal of the synchronization level 1a as a synchronization source, and entering a synchronization level 3; or,

6. The method of claim 5, wherein the clock synchronization of the UTC system as a synchronization source if the time service signal of the UTC system is received within the first time period comprises:

and if the synchronization signal sent by the terminal of the synchronization level 1a is not received within the first time length, but the time service signal of the UTC system is received, performing clock synchronization by using the UTC system as a synchronization source, and entering the synchronization level 1.

7. The method of any of claims 5 to 6, further comprising:

and if the synchronization signal sent by the base station or other terminals is not received in the first time length, entering a synchronization level 3 when a second time length after the first time length is up.

8. A terminal, comprising: a receiving module and a synchronization module;

the synchronization module is used for performing clock synchronization by using the universal coordinated time (UTC) system as a synchronization source and entering a synchronization level 1 if the receiving module receives a time service signal of the UTC system; otherwise, if the receiving module receives the synchronous signal within the first time length, performing clock synchronization by taking a terminal or a base station which sends the synchronous signal as a synchronization source according to the grade of the synchronous signal;

if the receiving module does not receive the time service signal of the UTC system within the first time period, but receives the downlink pilot signal sent by the base station of the synchronization level 0, the synchronization module is specifically configured to:

taking the base station of the synchronization level 0 as a synchronization source to carry out clock synchronization, and entering a synchronization level 2 or a synchronization level 3 according to a timing compensation enabling mark configured by the base station, wherein the timing compensation enabling mark is used for indicating whether timing compensation is enabled or not; if the timing compensation is enabled and the terminal performs clock synchronization based on the timing compensation performed by the distance calibration or the uplink synchronization calibration, entering a synchronization level 2, otherwise entering a synchronization level 3, and if the timing compensation is not enabled, entering the synchronization level 2;

9. The terminal of claim 8, wherein the synchronization module is specifically configured to:

10. The terminal of claim 8, wherein the synchronization module is further configured to:

and if the receiving module does not receive the time service signal of the UTC system in the first time length and does not receive the synchronous signal sent by the base station or other terminals, entering a synchronous grade 3 when a second time length after the first time length is up.

11. The terminal of claim 8, wherein the synchronization module is further configured to:

and if the receiving module of the terminal entering the synchronization level 1 receives the synchronization signal sent by the base station or other terminals, giving up the clock synchronization by taking the base station or other terminals sending the synchronization signal as a synchronization source.

12. A terminal, comprising: a receiving module and a synchronization module;

the synchronization module is configured to perform clock synchronization using the base station of the synchronization level 0 as a synchronization source and enter a synchronization level 1a if the receiving module receives a downlink pilot signal sent by the base station of the synchronization level 0; otherwise, if the receiving module receives a synchronization signal sent by other terminals or a time service signal of a universal coordinated time (UTC) system within a first time length, performing clock synchronization by taking the other terminals as synchronization sources or the UTC system as a synchronization source according to the synchronization levels of the other terminals;

the synchronization module is specifically configured to: if the receiving module receives a synchronization signal sent by a terminal of a synchronization level 1a within a first time length, performing clock synchronization by taking the terminal of the synchronization level 1a as a synchronization source, and entering a synchronization level 3; or,

13. The terminal of claim 12, wherein the synchronization module is specifically configured to:

if the receiving module does not receive the synchronization signal sent by the terminal of the synchronization level 1a within the first time length, but receives the time service signal of the UTC system, the UTC system is used as a synchronization source to carry out clock synchronization, and the UTC system enters the synchronization level 1.

14. The terminal of any of claims 12 to 13, wherein the synchronization module is further configured to:

and if the receiving module does not receive the synchronization signal sent by the base station or other terminals in the first time length, entering a synchronization level 3 when a second time length after the first time length is up.