Patent Description:
Currently, an in-vehicle device may obtain traffic information or receive an information service in time through vehicle-to-vehicle (Vehicle to Vehicle, V2V) communication, vehicle-to-infrastructure (Vehicle to Infrastructure, V2I) communication, vehicle-to-pedestrian (Vehicle to Pedestrian, V2P) communication, vehicle-to-network (Vehicle to Network, V2N) communication, and the like. V2V and V2I are used as a common example. An in-vehicle device may broadcast, to another surrounding in-vehicle device through the V2V communication, information such as a speed, a driving direction, or a specific position of the vehicle, or whether an emergency braking is performed, so that the driver can obtain such information to better know a status of traffic outside a line of sight, to discover early and avoid a risk. For the V2I communication, in addition to exchanges of the foregoing security information, a roadside infrastructure may further provide various types of service information for the in-vehicle device, enable the in-vehicle device to access a data network, charge the vehicle without stopping the vehicle, and provide in-vehicle entertainment, so that transportation is more intelligent. The foregoing communication manners may be collectively referred to as vehicle-to-everything (Vehicle-to-Everything, V2X) communication herein, data in V2X transmission is referred to as V2X data, and a network used for V2X communication is referred to as Internet of Vehicles.

A transmission carrier used by user equipment (User Equipment, UE) for V2X transmission and a service carrier on which the UE camps may be different carriers, in other words, the transmission carrier and the service carrier may be located on different frequencies.

When the transmission carrier and the service carrier are located on different frequencies, a base station may configure, by using the service carrier, a synchronization source for the transmission carrier used by the UE to transmit V2X data. The UE may obtain, based on the synchronization source, a synchronization clock on the transmission carrier, and transmit data. For example, the base station configures, for the UE, a global navigation satellite system (Global Navigation Satellite System, GNSS) as the synchronization source of the transmission carrier for the V2X data, and all resources configured by the base station for the UE are based on a synchronization source clock (namely, a GNSS clock). Based on a specific GNSS moment, the UE may calculate a frame number and a subframe number that are corresponding to the moment. When allocating a resource to the UE, based on the GNSS clock, the base station may indicate a specific time-frequency location of a transmission resource that may be used by the UE (for example, all frequency domain resources of a tenth subframe of a frame #<NUM> may be used to transmit V2X data). The UE may send data when a frame number and a subframe number that are corresponding to a current GNSS moment arrives at a moment of a resource allocated by the base station.

However, the UE may occasionally be out of synchronization with the synchronization source, in other words, synchronization between the UE and the synchronization source may fail. For example, when the UE enters a tunnel or a garage, the UE may not receive a signal sent by the GNSS. In this case, the UE cannot obtain a frame number and a subframe number. Consequently, the UE cannot determine a valid moment of a resource allocated by the base station, and the UE cannot transmit data normally.

<NPL>(sections <NUM>-<NUM>, <FIG>), discloses that remaining priority rules for synchronization sources and timing issues for V2V PC5, eNB instructs vehicle UE to prioritize either eNB-based synchronization or GNSS or GNSS-equivalent, the carrier that UE camps on can be different carrier other than the carrier that the priority is configured, UE can try to synchronize to SLSS associated with GNSS, if it cannot detect any, it can simply fall back to use the eNB timing reference.

<NPL>(sections <NUM>), discloses that whether eNB timing or GNSS timing is prioritized can be per carrier cell-specifically configured by the cell on which an UE camps, the carrier that UE camps on can be different carrier other than the carrier that the priority is configured. In these cases it is sometimes possible that the correct synchronization information is forwarded to the UE.

Embodiments of the present invention provide a data transmission method and apparatus, so as to implement normal data transmission after user equipment is out of synchronization with a synchronization source. The invention is described in the embodiments of the appended independent claims. Further detailed embodiments are given in the dependent claims.

The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are a part rather than all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

It should be understood that, the technical solutions of the embodiments of the present invention may be applied to various communications systems, such as: a Global System for Mobile Communications (Global System for Mobile Communications, GSM) system, a Code Division Multiple Access (Code Division Multiple Access, CDMA) system, a Wideband Code Division Multiple Access (Wideband Code Division Multiple Access, WCDMA) system, a general packet radio data (General Packet Radio Service, GPRS), a Long Term Evolution (Long Term Evolution, LTE) system, an LTE frequency division duplex (Frequency Division Duplex, FDD) system, an LTE time division duplex (Time Division Duplex, TDD), Universal Mobile Telecommunications System (Universal Mobile Telecommunications System, UMTS), and a Worldwide Interoperability for Microwave Access (Worldwide Interoperability for Microwave Access, WiMAX) communications system.

A base station may be a base station (Base Transceiver Station, BTS) in GSM or CDMA, a base station (NodeB, NB) in WCDMA, or may be an evolved NodeB (evolved NodeB, eNB or e-NodeB) in LTE. This is not limited in the embodiments of the present invention. However, for ease of description, a base station or an eNB is used as an example for description in the following embodiments.

User equipment (User Equipment, UE) may be referred to as a terminal (Terminal), a mobile station (Mobile Station, MS), a mobile terminal (Mobile Terminal), or the like. The user equipment may communicate with one or more core networks through a radio access network (Radio Access Network, RAN). For example, the user equipment may be a mobile phone (also referred to as a "cellular" phone) or a computer with a mobile terminal function. For example, the user equipment may be a portable, pocket-sized, handheld, computer built-in, or in-vehicle mobile apparatus, which exchanges voice and/or data with the radio access network. In particular, the user equipment in the embodiments of the present invention may be an in-vehicle device.

<FIG> is a schematic diagram of a scenario of a communications system applicable to an embodiment of the present invention. The communications system in <FIG> includes user equipment UE <NUM>, a device X <NUM>, an access network device <NUM>, and a synchronization source <NUM>.

The UE in this embodiment of the present invention may be an in-vehicle device, or may be a terminal-type roadside unit device, a handheld terminal, a wearable device, or the like. The access network device in this embodiment of the present invention may be a base station, a station-type roadside unit, or the like. The device X in this embodiment of the present invention may be any device. For example, the device X may be an in-vehicle device, a network, a pedestrian, a roadside infrastructure, or the like.

For example, the UE is an in-vehicle device and the access network device is a base station herein. V2X data transmission may be performed between the UE and the device X, and the UE <NUM> is within a signal coverage area of the base station <NUM>. A transmission carrier of the V2X data transmission may be different from a service carrier, deployed by the base station, on which the UE camps, in other words, frequencies of the transmission carrier and the service carrier may be different.

A synchronization source of the UE on a V2X data transmission carrier may be configured by using a service carrier. For example, the base station configures, for the UE, a GNSS as the synchronization source of the V2X data transmission carrier. All resources configured by the base station for the UE are based on a synchronization source GNSS clock. The UE may calculate, based on a GNSS moment, a frame number and a subframe number that are corresponding to the moment. When allocating a resource to the UE, the base station may indicate a specific time-frequency location of a transmission resource that may be used by the UE, for example, a frame number and a subframe number that are of the transmission resource that may be used by the UE. The UE may send data when a frame number and a subframe number that are corresponding to a GNSS moment are equal to the frame number and the subframe number that are of the transmission resource and that are indicated by the base station.

However, the UE may be out of synchronization with the synchronization source, in other words, synchronization between the UE and the synchronization source may fail. For example, when the UE enters a tunnel or a garage, the UE may not receive a signal sent by the GNSS. In this case, the UE cannot obtain a frame number and a subframe number. Consequently, the UE cannot determine a valid moment of a resource allocated by the base station, and the UE cannot transmit data normally.

When a service carrier and a data transmission carrier are located on different carriers and the UE does not synchronize with a current synchronization source allocated by the base station, how to ensure normal transmission of V2X data by the UE is a main technical problem to be resolved in the present invention.

<FIG> is a schematic interactive flowchart of a data transmission method according to an embodiment of the present invention. In description of this embodiment of the present invention, for example, an access network device is an eNB and data is V2X data. In a method procedure, information exchange between UE and an eNB and information exchange between the UE and a device X are used as examples for description of data transmission.

The eNB sends first synchronization source configuration information to the UE on a first carrier, and the UE receives the first synchronization source configuration information sent by the eNB on the first carrier.

The eNB sends the first synchronization source configuration information to the UE. The first synchronization source configuration information may be used to configure, for the UE, a current synchronization source required for transmitting V2X data on a second carrier.

In an optional embodiment, the first synchronization source configuration information carries an identifier of a first synchronization source, so that the UE determines, based on the identifier of the first synchronization source, the current synchronization source required for transmitting V2X data. The first synchronization source configuration information in this embodiment of the present invention may indicate that the first synchronization source is any one of a GNSS, a mobile terminal or a cell synchronized with a GNSS, a cell currently serving the UE, a specified cell, and a specified mobile terminal synchronization source. Preferably, the first synchronization source configuration information may indicate that the first synchronization source is a GNSS, and correspondingly the identifier of the first synchronization source is a GNSS identifier.

The eNB is deployed on the first carrier, and V2X data transmission is performed by using the second carrier. A frequency of the first carrier is different from a frequency of the second carrier. For example, the frequency of the first carrier (a service carrier of the UE) may be <NUM>, and the frequency of the second carrier (a transmission carrier used by the UE to transmit V2X data) may be <NUM>. The service carrier may be used to configure a transmission resource (for example, a dynamic transmission resource, a semi-persistent transmission resource, a transmission resource pool, and a receiving resource pool) on the transmission carrier for the UE. The configuration information may further include frequency information of the second carrier, so that a first UE may perform data transmission on the frequency of the second carrier. Optionally, no base station is deployed on the second carrier.

In an optional embodiment, the V2X data may be transmitted in a direct connection communication manner in which two devices directly communicate with each other, or may be transmitted in a communication manner in which a base station acts as a relay. Preferably, the V2X data is transmitted on the second carrier in the direct connection communication manner.

In an optional embodiment, the eNB may send the configuration information to the UE by using radio resource control (Radio Resource Control, RRC) dedicated signaling or a broadcast message.

In an optional embodiment, the UE may always be within a network coverage area of the eNB. When the UE detects that signal quality of the base station meets an access requirement, the UE in a connected state may normally exchange signaling and data with the base station, and the UE in an idle state may normally receive system information and paging information sent by the base station.

The UE determines a first synchronization source.

The UE receives the first synchronization source configuration information, and uses, based on the first synchronization source configuration information, the first synchronization source as a synchronization source for transmitting the V2X data.

When the first synchronization source configuration information carries the identifier of the first synchronization source, the UE may determine the first synchronization source based on the identifier of the first synchronization source.

In an optional implementation, the UE may further implement synchronization between the UE and the first synchronization source. For example, when the first synchronization source is a GNSS, the UE may directly synchronize with the GNSS system by using a GNSS receiver of the UE, or may search for a GNSS-dedicated direct-connection link synchronization signal to use a mobile terminal with a GNSS clock as an intermediate synchronization source, and synchronize with the intermediate synchronization source to implement synchronization with the GNSS system.

The UE may implement data transmission by using a corresponding resource and based on the synchronization source. For example, after synchronizing with the first synchronization source, the UE may receive resource allocation information sent by the base station. The resource allocation information indicates at least one of a dynamic transmission resource, a semi-persistent transmission resource, a sending resource pool, and a receiving resource pool that are available on a direct connection link. The resource allocation information herein is configured based on a clock of the first synchronization source. The UE transmits data by using a corresponding resource and based on the received resource allocation information. Specifically, the UE may send corresponding V2X data by using a sending resource and receive corresponding V2X data by using a receiving resource.

The UE determines that synchronization with the first synchronization source fails.

Step <NUM> indicates that the UE may implement data transmission by using a corresponding resource and based on the first synchronization source. However, the UE may be out of synchronization with the first synchronization source, for example, when the UE enters a tunnel or a garage.

The UE may determine a failure of the synchronization with the first synchronization source by using many methods, and a specific determining method is not limited in this embodiment of the present invention. For example, a synchronization timer on the UE may start timing when a latest synchronization signal is received. If the UE does not receive a synchronization signal from the first synchronization source when the synchronization timer of the UE exceeds a specified time, it may be considered that the synchronization between the UE and the first synchronization source fails. For another example, the UE may receive a synchronization signal from a synchronization source. When strength of a synchronization signal received by the UE from the first synchronization source is less than a first preset threshold, it may be considered that the synchronization between the UE and the first synchronization source fails. For still another example, when average strength of synchronization signals received by the UE from the first synchronization source in specified duration T is less than a second preset threshold, it may be considered that the synchronization between the UE and the first synchronization source fails.

In an optional embodiment, the failure of the synchronization between the UE and the first synchronization source may be that the UE is out of synchronization with the first synchronization source. Alternatively, when the UE detects a better synchronization source other than the first synchronization source, it may also be considered that the synchronization between the UE and the first synchronization source fails. For example, when the UE detects a second synchronization source, signal strength of the second synchronization source is greater than a third preset threshold, and a priority of the second synchronization source is higher than a priority of the first synchronization source, the UE may determine that the synchronization with the first synchronization source fails. When the UE detects a second synchronization source, signal strength of the second synchronization source is greater than a third preset threshold and signal strength of the first synchronization source is less than a fourth threshold, and a priority of the second synchronization source is equal to or less than a priority of the first synchronization source, the UE determines that the synchronization with the first synchronization source fails.

A priority of a synchronization source may be preconfigured by the system, or may be configured by the base station, for example, the base station sends system broadcast information to the UE on the first carrier for configuration, or the base station sends radio resource control RRC dedicated signaling to the UE on the first carrier for configuration.

The UE determines a second synchronization source and a transmission resource.

In an optional embodiment, when the UE detects the better synchronization source other than the first synchronization source and then determines that the synchronization between the UE and the first synchronization source fails in step <NUM>, the UE may directly determine the detected better synchronization source as the second synchronization source in step <NUM>. In addition, a transmission resource may be allocated based on a clock of the second synchronization source. The transmission resource herein may be configured by the base station or may be preconfigured by the system.

In an optional embodiment, the second synchronization source and a corresponding transmission resource may be obtained through preconfiguration or may be obtained by the base station through signaling configuration. The signaling configuration of the base station may be that the UE receives, on the first carrier, signaling configuration information sent by the base station.

Specifically, the UE may determine, in the following manner, the second synchronization source required for transmitting V2X data. The UE obtains second synchronization source configuration information sent by the access network device on the first carrier, the second synchronization source configuration information may carry an identifier of the second synchronization source, and the UE may determine, based on the identifier of the second synchronization source, the second synchronization source required for transmitting V2X data. The second synchronization source configuration information sent by the access network device to the UE may be configured by using a broadcast message or may be configured by sending radio resource control RRC dedicated signaling. Alternatively, the UE may obtain, by using preconfigured information, second synchronization source configuration information that carries an identifier of the second synchronization source, and determine, based on the identifier of the second synchronization source, the second synchronization source required for transmitting V2X data. Alternatively, the UE may use a clock of the UE as the second synchronization source.

In an optional embodiment, the clock of the UE may be a clock or a timer currently independently maintained inside the UE. In an optional embodiment, the UE may use a clock of the current base station as the clock of the UE, or may independently determine a clock as the clock of the UE.

The UE may determine, in the following manner, a transmission resource required for transmitting V2X data. The UE obtains resource pool configuration information, determines a transmission resource pool based on the transmission resource pool configuration information, and determines the transmission resource based on the transmission resource pool. The resource pool configuration information may be preconfigured information, or may be configured by the access network device by using signaling. The resource pool configuration information indicates available transmission resource pools, for example, a receiving resource pool or a sending resource pool. In an optional embodiment, the UE may randomly select one resource pool from the available resource pools, and select one resource from the selected resource pool as the transmission resource for transmitting the data on the second carrier, in other words, performing corresponding data transmission or reception.

In addition, the transmission resource in this embodiment of the present invention may be a dynamic transmission resource or a semi-persistent transmission resource. Specifically, the UE may alternatively determine, in the following manner, the transmission resource required for transmitting V2X data. The UE receives resource scheduling information sent by the access network device, and determines the transmission resource based on the resource scheduling information, so that the UE may transmit the data on the second carrier by using the determined transmission resource and based on the second synchronization source. The resource scheduling information herein is used for dynamic resource scheduling or semi-persistent resource scheduling. In the semi-persistent resource scheduling in this embodiment of the present invention, a resource number during first scheduling may be specified, and a change rule or period of a resource number during each scheduling may be specified, so as to perform semi-persistent resource scheduling at intervals of a specified quantity of resources. The dynamic resource scheduling in this embodiment of the present invention means that a resource is dynamically scheduled each time the resource is used.

In an optional embodiment, the UE determines the transmission resource by using the clock of the second synchronization source as a reference synchronization clock.

The UE transmits data on a transmission carrier (for example, a second carrier) by using the transmission resource and based on the second synchronization source determined in step <NUM>, and the device X receives, on the second carrier, the data transmitted by the UE.

In this embodiment of the present invention, that the UE transmits data on the transmission carrier may be that the UE sends data or that the UE receives data. A corresponding transmission resource may be a sending resource or a receiving resource.

Herein, that the UE transmits the data on the second carrier is that the UE performs data transmission with another device (for example, the device X). The UE in this embodiment of the present invention may be an in-vehicle device, and the device X may be an in-vehicle device, a network, a roadside infrastructure, a handheld terminal of a pedestrian, or the like. Data transmitted between the UE and the device X may be V2X data.

The UE sends, to the eNB, indication information indicating that synchronization fails, and the eNB receives the indication information indicating that synchronization fails, which is sent by the UE.

Step <NUM> is an optional step. In an optional embodiment, after determining that the first synchronization source fails in step <NUM>, the UE may feed back the indication information to the eNB, and the indication information is used to indicate that the synchronization between the UE and the first synchronization source fails. The UE feeds back a synchronization failure to the eNB, so that the eNB does not need to send signaling, a configuration resource, and the like to the UE, so as to reduce signaling overheads. Certainly, the eNB may also send new synchronization source configuration information to the eNB, and optionally, the new synchronization source configuration information may be the second synchronization source configuration information.

It should be understood that step <NUM> may be performed before step <NUM> in which the new second synchronization source is re-determined, or step <NUM> may be performed after step <NUM>, or step <NUM> and step <NUM> may be performed at the same time. This is not limited in this embodiment of the present invention.

The UE sends identification information of the second synchronization source to the eNB, and the eNB receives the identification information of the second synchronization source, which is sent by the UE.

Step <NUM> is an optional step. In an optional embodiment, after re-determining the new second synchronization source in step <NUM>, the UE may further send the identification information of the second synchronization source to the eNB. The identification information of the second synchronization source may carry the identifier of the second synchronization source, and may be used to instruct the UE to use the clock of the second synchronization source as a synchronization clock required for transmitting the data on the second carrier. In this way, after receiving the identification information of the second synchronization source, the eNB may record related information of a current synchronization source (the second synchronization source) of the UE in the eNB, so that the eNB obtains a new synchronization source and uses a clock of the new synchronization source as a synchronization clock for resource configuration.

In particular, the data in this embodiment of the present invention may be V2X data.

In this embodiment of the present invention, user equipment determines, based on synchronization source information configured by a base station, a synchronization source required for transmitting data. After being out of synchronization with the synchronization source, the UE re-determines a new synchronization source, and uses the new synchronization source for data transmission. In this way, when frequencies of a transmission carrier and a service carrier are different, normal data transmission can still be implemented after the UE is out of synchronization with an original synchronization source.

It should be understood that sequence numbers of steps in the procedure do not constitute a constraint or limitation on a time sequence of performing the steps. For example, step <NUM> may be performed at any moment after step <NUM> in which the new second synchronization source is re-determined, for example, step <NUM> is performed before or after step <NUM> in which data is transmitted, or step <NUM> and step <NUM> are performed at the same time. This is not limited in this embodiment of the present invention.

The foregoing embodiment is merely intended to help a person skilled in the art better understand the present invention, but is not intended to limit the protection scope of the present invention.

<FIG> is a schematic interactive flowchart of a data transmission method according to another embodiment of the present invention. To describe data transmission in this embodiment of the present invention, for example, an access network device is an eNB, V2X data is transmitted, and information is exchanged between UE and the eNB.

The eNB sends first synchronization source configuration information to the user equipment UE on a first carrier, and the UE receives the first synchronization source configuration information sent by the eNB on the first carrier.

The first synchronization source configuration information may carry an identifier of a first synchronization source. The eNB is deployed on the first carrier. The UE (for example, an eNB) receives the first synchronization source configuration information sent by a base station. The UE may synchronize with the first synchronization source based on the first synchronization source configuration information, and transmit data on a second carrier based on the first synchronization source.

The UE sends indication information to the eNB on the first carrier, and the eNB receives, on the first carrier, the indication information sent by the UE.

The indication information is used to indicate that the synchronization between the UE and the first synchronization source fails. After detecting that the synchronization with the first synchronization source fails, the UE may send the indication information to the eNB. For a method for determining a synchronization failure by the UE, refer to description in step <NUM> in <FIG>. Details are not described herein again to avoid repetition.

The access network device in this embodiment of the present invention configures a synchronization source for the UE, and after synchronization between the UE and the synchronization source fails, receives indication information that is sent by the UE and that indicates that the synchronization with the synchronization source fails. In this way, after the synchronization between the UE and the synchronization source fails, based on the indication information, the access network device may skip sending signaling to the UE or configuring a resource corresponding to the first synchronization source for the UE, so as to save a signaling overhead.

The eNB may send second synchronization source configuration information to the UE on the first carrier, and the UE receives, on the first carrier, the second synchronization source configuration information sent by the eNB.

The second synchronization source configuration information is used by the UE to determine a second synchronization source based on the second synchronization source configuration information after the synchronization with the first synchronization source fails, and transmit the data on the second carrier based on the second synchronization source. A frequency of the first carrier is different from a frequency of the second carrier.

Step <NUM> is an optional step. After receiving the indication information indicating a synchronization failure, the eNB may reconfigure a synchronization source for the UE, for example, by sending the second synchronization source configuration information to the UE on the first carrier. The second synchronization source configuration information may include an identifier of the second synchronization source. After receiving the second synchronization source configuration information, the UE may synchronize with the second synchronization source based on the second synchronization source configuration information, so as to continue to transmit the data on the second carrier based on the second synchronization source, and ensure normal data transmission.

In an optional embodiment, if the second synchronization source is preconfigured, after the UE synchronizes with the second synchronization source, the eNB may receive identification information that is of the second synchronization source and that is sent by the UE, so that the base station obtains an identifier of a new synchronization source (the second synchronization source), and configures a transmission resource corresponding to the second synchronization source for the second synchronization source.

Step <NUM> is an optional step. In an optional embodiment, the access network device (for example, an eNB) may further send the second synchronization source configuration information to the UE on the first carrier. The second synchronization source configuration information is used by the UE to determine the second synchronization source based on the second synchronization source configuration information after the synchronization with the first synchronization source fails, and transmit the data on the second carrier based on the second synchronization source. The frequency of the first carrier is different from the frequency of the second carrier. This may ensure that after the synchronization between the UE and the first synchronization source fails, the access network device can learn of a new synchronization source (for example, the second synchronization source), so as to configure a transmission resource corresponding to the second synchronization source for the second synchronization source.

In an optional embodiment, the access network device may configure, for the UE, a transmission resource corresponding to the second synchronization source, and send the transmission resource to the UE, so that the UE transmits data on the transmission resource based on the second synchronization source. In this way, the UE can still perform normal data transmission after the synchronization with the first synchronization source fails.

In an optional embodiment, the data is vehicle-to-everything V2X communication data.

The foregoing describes in detail the data transmission method according to the embodiments of the present invention with reference to <FIG> and <FIG>. The following describes block diagrams of a data transmission apparatus according to an embodiment of the present invention with reference to <FIG>.

<FIG> is a block diagram of a data transmission apparatus according to an embodiment of the present invention. The apparatus in <FIG> may perform steps performed by the UE in the method embodiment in <FIG>. An apparatus <NUM> in <FIG> includes a receiving unit <NUM>, a processing unit <NUM> and a transmission unit <NUM>.

The receiving unit <NUM> is configured to receive first synchronization source configuration information on a first carrier, where the first synchronization source configuration information is used to determine a first synchronization source.

The processing unit <NUM> is configured to: determine the first synchronization source based on the first synchronization source configuration information received by the receiving unit; determine that synchronization with the first synchronization source fails; and determine a second synchronization source and a transmission resource. The first synchronization source is used to provide a synchronization clock required for transmitting data on a second carrier, and a frequency of the first carrier is different from a frequency of the second carrier.

The transmission unit <NUM> is configured to transmit the data on the second carrier by using the transmission resource and based on the second synchronization source determined by the processing unit.

By using the foregoing solution, the user equipment determines, based on synchronization source information configured by a base station, a synchronization source required for transmitting data. After being out of synchronization with the synchronization source, the UE re-determines a new synchronization source, and uses the new synchronization source for data transmission. In this way, when frequencies of a transmission carrier and a service carrier are different, normal data transmission can still be implemented after the UE is out of synchronization with an original synchronization source.

The data transmission apparatus in this embodiment of the present invention may be applied to specific steps and an execution procedure of the UE in the data transmission method of the embodiments of the present invention, and units/modules of the apparatus and other operations and/or functions described above are respectively for implementing corresponding procedures of the UE in the method shown in <FIG>. Details are not described herein again for brevity.

In an optional embodiment, the receiving unit may be a receiver, the processing unit may be a processor, the transmission unit can be a transmitter. The receiver, the processor, and the transmitter may be configured to respectively perform methods performed by the receiving unit, the processing unit, and the transmission unit. Details are not described again to avoid repetition.

<FIG> is a block diagram of a data transmission apparatus according to another embodiment of the present invention. The apparatus in <FIG> may perform steps performed by the eNB in the method embodiments in <FIG> and <FIG>. An apparatus <NUM> in <FIG> includes a sending unit <NUM> and a receiving unit <NUM>.

The sending unit <NUM> is configured to send first synchronization source configuration information to user equipment UE by using a first carrier. The first synchronization source configuration information carries an identifier of a first synchronization source, and the first configuration information is used to determine the first synchronization source.

The receiving unit <NUM> is configured to receive indication information sent by the UE. The indication information is used to indicate that synchronization between the UE and the first synchronization source fails. The first synchronization source is used to provide the UE with a synchronization clock required for transmitting data on a second carrier. A frequency of the first carrier is different from a frequency of the second carrier.

By using the foregoing solution, the access network device configures a synchronization source for the UE, and after synchronization between the UE and the synchronization source fails, may receive indication information that is sent by the UE and that indicates that the synchronization with the synchronization source fails. In this way, after the synchronization between the UE and the synchronization source fails, based on the indication information, the access network device may skip sending signaling to the UE or configuring a resource corresponding to the first synchronization source for the UE, so as to save a signaling overhead.

In an optional embodiment, the sending unit <NUM> is further configured to send second synchronization source configuration information to the UE on the first carrier. The second synchronization source configuration information is used by the UE to determine a second synchronization source based on the second synchronization source configuration information after the synchronization with the first synchronization source fails, and transmit the data on the second carrier based on the second synchronization source.

In an optional embodiment, the eNB may reconfigure a synchronization source for the UE after receiving the indication information indicating a synchronization failure, for example, send the second synchronization source configuration information to the UE on the first carrier. The second synchronization source configuration information may include an identifier of the second synchronization source. After receiving the second synchronization source configuration information, the UE may synchronize with the second synchronization source based on the second synchronization source configuration information, so as to continue to transmit the data on the second carrier based on the second synchronization source, and ensure normal data transmission.

The data transmission apparatus in this embodiment of the present invention may be applied to specific steps and an execution procedure of the eNB in the data transmission method of the embodiments of the present invention, and units/modules of the apparatus and other operations and/or functions described above are respectively for implementing corresponding procedures of the eNB in the method shown in <FIG>. Details are not described herein again for brevity.

In an optional embodiment, the receiving unit may be a receiver and the sending unit may be a transmitter. The receiver and the transmitter may be configured to respectively perform methods performed by the receiving unit and the sending unit. Details are not described again to avoid repetition.

<FIG> is a block diagram of a data transmission apparatus according to another embodiment of the present invention. An apparatus <NUM> in <FIG> includes a transmitter <NUM>, a receiver <NUM>, and a processor <NUM>. The processor <NUM> controls an operation of the apparatus <NUM> and may be configured to process a signal.

The method disclosed in the foregoing embodiments of the present invention may be applied to the processor <NUM>, or may be implemented by the processor <NUM>. In an implementation process, steps in the foregoing method may be completed by using an integrated logic circuit of hardware or an instruction in a form of software in the processor <NUM>. The processor <NUM> may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or another programmable logic device, a discrete gate or a transistor logic device, or a discrete hardware component, and may implement or perform methods, steps, and logic block diagrams that are disclosed in the embodiments of the present invention. The general-purpose processor may be a microprocessor, any conventional processor, or the like. The steps of the methods disclosed with reference to the embodiments of the present invention may be directly implemented by using a hardware processor, or may be implemented by using a combination of hardware and a software module in the processor.

Specifically, the receiver <NUM> may receive first synchronization source configuration information on a first carrier. The first synchronization source configuration information is used to determine a first synchronization source.

The processor <NUM> may determine the first synchronization source based on the first synchronization source configuration information; determine that synchronization with the first synchronization source fails; and determine a second synchronization source and a transmission resource. The first synchronization source is used to provide UE with a synchronization clock required for transmitting data on a second carrier. A frequency of the first carrier is different from a frequency of the second carrier.

The transmitter <NUM> may transmit the data on the second carrier by using the transmission resource and based on the second synchronization source.

<FIG> is a block diagram of a data transmission apparatus according to another embodiment of the present invention. An apparatus <NUM> in <FIG> includes a transmitter <NUM> and a receiver <NUM>.

Specifically, the transmitter <NUM> may send first synchronization source configuration information to user equipment UE by using a first carrier, where the first synchronization source configuration information carries an identifier of a first synchronization source, and the first synchronization source configuration information is used to determine the first synchronization source.

The receiver <NUM> may receive indication information sent by the UE. The indication information is used to indicate that synchronization between the UE and the first synchronization source fails. The first synchronization source is used to provide the UE with a synchronization clock required for transmitting data on a second carrier. A frequency of the first carrier is different from a frequency of the second carrier.

In an optional embodiment, the transmitter <NUM> may further be configured to send second synchronization source configuration information to the UE on the first carrier. The second synchronization source configuration information is used by the UE to determine a second synchronization source based on the second synchronization source configuration information after the synchronization with the first synchronization source fails, and transmit the data on the second carrier based on the second synchronization source.

It should be understood that "an embodiment" mentioned in the whole specification does not mean that particular features, structures, or characteristics related to the embodiment are included in at least one embodiment of the present invention. Therefore, "in an embodiment" or "in an embodiment" appearing throughout the specification does not refer to a same embodiment. In addition, these particular features, structures, or characteristics may be combined in one or more embodiments by using any appropriate manner.

It should be understood that sequence numbers of the foregoing processes do not mean execution sequences in various embodiments of the present invention. The execution sequences of the processes should be determined according to functions and internal logic of the processes, and should not be construed as any limitation on the implementation processes of the embodiments of the present invention.

It should be understood that in the embodiments of the present invention, "B corresponding to A" indicates that B is associated with A, and B may be determined based on A. However, it should further be understood that determining A based on B does not mean that B is determined based on A only; in other words, B may be determined based on A and/or other information.

The term "and/or" in this specification describes only an association relationship for describing associated objects and represents that three relationships may exist.

When the functions are implemented in the form of a software functional unit and sold or used as an independent product, the functions may be stored in a computer-readable storage medium. Based on such an understanding, the technical solutions of the present invention essentially, or the part contributing to the prior art, or some of the technical solutions may be implemented in a form of a software product. The computer software product is stored in a storage medium, and includes several instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform all or some of the steps of the methods described in the embodiments of the present invention. The foregoing storage medium includes: any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), a magnetic disk, or an optical disc.

Claim 1:
A data transmission method, comprising:
receiving (<NUM>), by user equipment, UE, first synchronization source configuration information on a first carrier, wherein the first synchronization source configuration information is used for determining a first synchronization source;
determining (<NUM>), by the UE, the first synchronization source based on the first synchronization source configuration information, wherein the first synchronization source is used for providing a synchronization clock required for transmitting data on a second carrier for the UE, and a frequency of the first carrier is different from a frequency of the second carrier;
determining (<NUM>), by the UE, a second synchronization source and a transmission resource, the transmission resource is associated with the second synchronization source, determining (<NUM>), by the UE, that a synchronization with the first synchronization source fails when the signal strength of the second synchronization source is greater than a first preset threshold and signal strength of the first synchronization source is less than a second threshold and a priority of the second synchronization source is equal to or less than a priority of the first synchronization source; and
transmitting (<NUM>), by the UE, the data on the transmission resource of the second carrier and based on the second synchronization source.