Patent Description:
In a wireless communication system, in a communication system such as a long term evolution (long term evolution, LTE) system, data transmission can be performed only after a radio resource control (radio resource control, RRC) connection is established between a terminal device and a network device. A process of setting up the RRC connection can be completed only after the terminal device exchanges a plurality of pieces of signaling with the network device, and this causes relatively large signaling overheads.

However, in a machine type communication (machine type communication, MTC) system or a narrowband internet of things (narrow band internet of things, NB-IoT) system, data transmission is characterized by a relatively small data volume and frequent data transmission. To reduce signaling overheads, a technology of performing data transmission before an RRC connection is established is proposed. For example, data transmission is performed in a random access process. This technology may be referred to as an early data transmission (early data transmission, EDT) technology.

Currently, in the EDT technology, downlink data is sent to the terminal device by using a message <NUM> in the random access process. There is other signaling before the message <NUM>, and this results in a data transmission delay. Therefore, how to reduce the data transmission delay in the EDT technology is a technical problem to be urgently resolved currently.

The document <NPL>, discusses general aspects that should be considered in evaluating the following four options: Option <NUM>. MT data in paging message; Option <NUM>. MT data scheduled in paging message; Option <NUM>. MT data after paging message and PRACH preamble transmission, i.e., MT data with Msg2; Option <NUM>. MT data in Msg4.

The document <NPL>, describes that in a MT call for an IDLE UE, the first downlink message is the paging message from the network. Once the UE receives paging message (i.e., when a paging record corresponding to UE's NAS identity is present), it initiates random access procedure. Therefore, the MT-initiated early data transmission in DL can be achieved by various options: option <NUM> - Including MT data in the paging message; option <NUM> - MT data after paging; option <NUM> - MT data after paging and PRACH preamble.

The document <NPL>, discusses early DL data transmission. In one solution a paging message is sent by the network and the DL data are either scheduled or directly sent in MSG2.

The invention is defined by the appended claims and provides data transmission methods, a communication apparatus and a computer program product, to reduce a data transmission delay in an EDT technology.

As defined by claim <NUM>, the invention provides a data transmission method, comprising: sending, by an access network device, a paging message to a terminal device, wherein the paging message comprises a first indication and does not comprise a temporary cell radio network temporary identity TC-RNTI; receiving, by the access network device, a random access preamble from the terminal device, wherein the random access preamble corresponds to the first indication; and sending, by the access network device in response to the random access preamble, a random access response message RAR to the terminal device, wherein the random access response message RAR comprises a first field and downlink data and a temporary cell radio network temporary identity TC-RNTI and wherein the first field indicates that the random access response message RAR carries the downlink data, and wherein the response message indicates that the access network device successfully receives the random access preamble.

In the foregoing technical solution, the response message that carries the downlink data and that is sent by the access network device to the terminal device may be understood as a second message (message <NUM>, MSG2) in a random access process. In other words, in embodiments of this application, the downlink data is sent to the terminal device by using the MSG2, so that the terminal device receives the downlink data as early as possible, thereby reducing a data transmission delay.

Further, in the foregoing technical solution, the temporary cell radio network temporary identity (temporary cell radio network temporary identity, TC-RNTI) is carried in the response message responding to the random access preamble, that is, the TC-RNTI does not need to be carried in the paging message, so that more bits in the paging message are used to indicate a paging capacity. In this way, the paging capacity of the paging message can be increased.

In the foregoing technical solution, an RAR in a current technology may be still used to carry downlink data, and an implementation is simple.

In the foregoing technical solution, the response message is sent after the terminal device sends the random access preamble, and if the access network device fails to receive the preamble sent by the terminal device, the access network device does not send the response message to the terminal device. Therefore, from this perspective, the response message may be further used to indicate that the access network device successfully receives the preamble sent by the terminal device. In other words, the response message is an acknowledgement (acknowledge, ACK) message of the preamble. This can avoid a problem in the current technology that the downlink data fails to be received because the terminal device cannot learn whether the access network device successfully receives the preamble.

As defined by claim <NUM>, the invention provides a data transmission method, comprising: sending, by an access network device, a paging message to a terminal device, wherein the paging message comprises a first indication and does not comprise a temporary cell radio network temporary identity TC-RNTI; receiving, by the access network device, a random access preamble from the terminal device, wherein the random access preamble corresponds to the first indication; sending, by the access network device in response to the random access preamble, a random access response RAR to the terminal device, wherein the RAR comprises a temporary cell radio network temporary identity TC-RNTI, and wherein the RAR indicates that the access network device successfully receives the preamble sent by the terminal device; and sending, by the access network device, downlink data to the terminal device after sending the RAR, wherein the access network device first sends, to the terminal device, a second indication that indicates a location of a time-frequency resource of the downlink data.

In the foregoing technical solution, after sending the RAR, the access network device sends the downlink data to the terminal device. Compared with a solution, in a current technology, of sending the downlink data to the terminal device by using the message <NUM>, the downlink data is sent earlier, so that the terminal device receives the downlink data as early as possible, thereby reducing a data transmission delay.

Further, the access network device includes the TC-RNTI in the RAR, that is, the TC-RNTI does not need to be carried in the paging message, so that more bits in the paging message are used to indicate a paging capacity. In this way, the paging capacity of the paging message can be increased. In addition, because the RAR is sent after the terminal device sends the preamble, from this perspective, the RAR may be further used to indicate that the access network device successfully receives the preamble sent by the terminal device. In this way, this can avoid a problem in the current technology that the downlink data fails to be received because the terminal device cannot learn whether the access network device successfully receives the preamble.

Claim <NUM> defines an embodiment of the data transmission method of claim <NUM>, wherein the RAR sent to the terminal device comprises a downlink assignment DL-assignment; wherein the sending, by the access network device, the downlink data to the terminal device comprises sending the downlink data on a time-frequency resource indicated by the DL-assignment.

In the foregoing technical solution, after sending the RAR, the access network device sends the downlink data to the terminal device on the time-frequency resource indicated by the DL-assignment carried in the RAR. Compared with a solution, in a current technology, of sending the downlink data to the terminal device by using the message <NUM>, the downlink data is sent earlier, so that the terminal device receives the downlink data as early as possible, thereby reducing a data transmission delay.

Claim <NUM> defines an embodiment of the method according to claim <NUM>, wherein before the sending, by the access network device, downlink data to the terminal device, the method comprises scrambling, by the access network device, the second indication by using the TC-RNTI.

As defined by claim <NUM>, the invention provides a data transmission method, comprising: receiving, by a terminal device, a paging message from an access network device, wherein the paging message comprises a first indication and does not comprise a temporary cell radio network temporary identity TC-RNTI; sending, by the terminal device in response to the paging message, a random access preamble to the access network device, wherein the random access preamble corresponds to the first indication; and receiving, by the terminal device, a response message from the access network device, wherein the response message comprises downlink data and a temporary cell radio network temporary identity TC-RNTI, wherein the response message is a random access response RAR, the RAR comprises a first field, and the first field indicates that the RAR carries the downlink data, and wherein the response message further indicates that the access network device successfully receives the random access preamble.

As defined by claim <NUM>, the invention provides a data transmission method, comprising: receiving, by a terminal device, a paging message from an access network device, wherein the paging message comprises a first indication and does not comprise a temporary cell radio network temporary identity TC- RNTI; sending, by the terminal device in response to the paging message, a random access preamble to the access network device, wherein the random access preamble corresponds to the first indication; receiving, by the terminal device, a random access response RAR from the access network device, wherein the RAR comprises a temporary cell radio network temporary identity TC-RNTI, and wherein the RAR indicates that the access network device successfully receives the preamble sent by the terminal device; and receiving, by the terminal device, downlink data after receiving the RAR. , wherein the terminal first receives, from the access network device, a second indication that indicates a location of a time-frequency resource of the downlink data.

Claim <NUM> defines an embodiment of the data transmission method according to claim <NUM>, wherein the RAR comprises a downlink assignment DL-assignment; and wherein the downlink data received by the terminal device is received on a time-frequency resource indicated by the DL-assignment.

Claim <NUM> defines an embodiment of the method according to claim <NUM>, wherein the RAR comprises a second field that indicates a UL-grant, and the DL-assignment is indicated by the second field.

Claim <NUM> defines an embodiment of the method according to claim <NUM>, wherein before the receiving, by the terminal device, downlink data, the method further comprises monitoring, by the terminal device, a downlink control channel by using the TC-RNTI, to obtain the second indication.

As defined by claim <NUM>, the invention provides a communication apparatus, comprising: a processor, wherein the processor is coupled to a memory; and the memory, configured to store a computer program, wherein the processor is configured to execute the computer program stored in the memory to cause the communication apparatus to perform the method according to any one of claims <NUM> to <NUM>.

As defined by claim <NUM>, the invention provides a computer program product, comprising computer-readable instructions which, when read and executed by a processor of a communication apparatus, cause the communication apparatus to perform the method according to any one of claims <NUM> to <NUM>.

To make objectives, technical solutions, and advantages of the embodiments of this application clearer, the following further describes the embodiments of this application in detail with reference to the accompanying drawings.

In the following descriptions, some terms in the embodiments of this application are described, to help a person skilled in the art have a better understanding.

The terminal may communicate with a core network through a radio access network (radio access network, RAN), and exchange a voice and/or data with the RAN. The terminal may include user equipment (user equipment, UE), a wireless terminal, a mobile terminal, a subscriber unit (subscriber unit), a subscriber station (subscriber station), a mobile station (mobile station), a remote station (remote station), an access point (access point, AP), a remote terminal (remote terminal), an access terminal (access terminal), a user terminal (user terminal), a user agent (user agent), a user device (user device), or the like.

For example, the terminal may include a mobile phone (or referred to as a "cellular" phone), a computer with a mobile terminal, a portable, pocket-sized, handheld, computer built-in, or in-vehicle mobile apparatus, and an intelligent wearable device. For example, the terminal device is a device such as a personal communications service (personal communication service, PCS) phone, a cordless phone, a session initiation protocol (session initiation protocol, SIP) phone, a wireless local loop (wireless local loop, WLL) station, or a personal digital assistant (personal digital assistant, PDA).

Alternatively, the terminal device may further include a limited device, for example, a device with low power consumption, a device with a limited storage capability, or a device with a limited computing capability. For example, the terminal device includes an information sensing device, for example, a barcode, radio frequency identification (radio frequency identification, RFID), a sensor, a global positioning system (global positioning system, GPS), or a laser scanner.

By way of example and not limitation, in the embodiments of this application, an intelligent wearable device is a generic term for wearable devices such as glasses, gloves, watches, clothes, and shoes that are developed based on intelligent design of daily wearing by using wearable technologies. The intelligent wearable device is a portable device that can be directly worn by a user or integrated into clothes or an accessory of a user.

The intelligent wearable device is not only a hardware device, but is used to implement powerful functions through software support, data exchange, and cloud interaction. In a broad sense, the intelligent wearable device includes full-featured and large-sized devices that can implement all or some functions without depending on smartphones, for example, smart watches or smart glasses, and devices that focus on only one type of application function and need to work with other devices such as smartphones, for example, various smart bands, smart helmets, or smart jewelry for monitoring physical signs.

Alternatively, the terminal may be a virtual reality (virtual reality, VR) device, an augmented reality (augmented reality, AR) device, a wireless terminal in industrial control (industrial control), a wireless terminal in self driving (driverless), a wireless terminal in remote medical surgery (remote medical surgery), a wireless terminal in a smart grid (smart grid), a wireless terminal in transportation safety (transportation safety), a wireless terminal in a smart city (smart city), a wireless terminal in a smart home (smart home), or the like.

(<NUM>) A (radio) access network ((radio) access network, (R)AN) device, for example, including a base station (for example, an access point), may be a device that communicates, on an air interface, with a wireless terminal through one or more cells in an access network. The (radio) access network device may be configured to perform mutual conversion between a received over-the-air frame and an internet protocol (IP) packet, and serve as a router between a terminal device and a remaining portion of the access network, and the remaining portion of the access network may include an IP network. The (radio) access network device may further coordinate attribute management of the air interface.

For example, the (radio) access network device may include a radio network controller (radio network controller, RNC), a NodeB (Node B, NB), a base station controller (base station controller, BSC), a base transceiver station (base transceiver station, BTS), a home base station (for example, a home evolved NodeB, or a home Node B, HNB), a baseband unit (base band unit, BBU), or a wireless fidelity (wireless fidelity, Wi-Fi) access point (access point, AP).

The (radio) access network device may also include a long term evolution (long term evolution, LTE) system, an LTE-Advanced (LTE-Advanced, LTE-A) system, or an evolved base station (NodeB, eNB, or e-NodeB, evolutional Node B) in a 4th generation mobile communication technology (the 4th generation mobile communication technology, <NUM>) system.

Alternatively, the (radio) access network device may include a next generation NodeB (next generation node B, gNB), a transmission reception point (transmission and reception point, TRP), or a transmission point (transmission point, TP) in a <NUM> system or a new radio (new radio, NR) system.

Alternatively, the (radio) access network device may include a centralized unit (centralized unit, CU) and/or a distributed unit (distributed unit, DU) in a cloud access network (cloud radio access network, CloudRAN) system. This is not limited in the embodiments of this application. In the embodiments of this application, the technical terms "(radio) access network device" and "access network device" may be used interchangeably.

(<NUM>) A core network (core network, CN) device is connected to a plurality of access networks, and includes a circuit switched (Circuit Switched, CS) domain and/or a packet switched (Packet Switched, PS) domain. CS network elements are a mobile switching center, a visited location register, and a gateway mobile switching center, and PS network elements are a general packet radio service (general packet radio service, GPRS) node and a gateway GPRS support node. Some network elements such as a home location register, the visited location register, and an authentication center may be shared by the CS domain and the PS domain.

(<NUM>) "A plurality of" in the embodiments of this application means two or more than two. In view of this, "a plurality of' in the embodiments of this application may also be understood as "at least two". The term "at least one" may be understood as one or more, for example, understood as one, two, or more.

For example, including at least one means including one, two, or more, and does not limit which are included. For example, including at least one of A, B, and C means that A, B, C, A and B, A and C, B and C, or all of A, B, and C may be included.

The term "and/or" describes an association relationship between associated objects and indicates that three relationships may exist. For example, A and/or B may indicate the following three cases: Only A exists, both A and B exist, and only B exists.

In addition, unless otherwise specified, the character "/" generally indicates an "or" relationship between associated objects. The terms "system" and "network" may be used interchangeably in the embodiments of this application.

Unless otherwise stated on the contrary, ordinal numerals such as "first" and "second" in the embodiments of this application are used to distinguish between a plurality of objects, and are not intended to limit a sequence, a time sequence, a priority, or an importance degree of the plurality of objects.

The foregoing describes some concepts in the embodiments of this application. The following describes technical features in the embodiments of this application.

An MTC system or an NB-IoT system is a component of a next generation communication system, for example, a <NUM> system, and has rapidly increasing market requirements. Compared with a conventional cellular network, in the MTC system or the NB-IoT system, there are more connected terminal devices. For example, for internet of things terminal devices such as smart water/electricity meters, smart households, cars, or wearable devices that are deployed on a large scale, there may be a large quantity of terminal devices (for example, more than tens of thousands) of the foregoing types under one NB-IoT base station. In addition, a service volume of the terminal device is relatively large, and a data packet generated by a service is smaller.

In the conventional cellular network, when a terminal device communicates with an access network device, radio resource control (radio resource control, RRC) needs to be established. However, an RRC connection establishment process can be completed only after the terminal device exchanges a plurality of pieces of signaling with the network device. Therefore, to reduce signaling overheads in the MTC system or the NB-IoT system, an EDT technology is proposed. In this way, before setting up an RRC connection, the terminal device can perform transmission of a data packet of a small data volume with the access network device.

<FIG> is a flowchart of an example of an EDT technology in a current technology.

S101: An eNB sends EDT configuration information.

The eNB may indicate, by using a system information block (system information block, SIB), the EDT configuration information allocated to UE. The EDT configuration information may include an EDT physical random access channel (physical random access channel, PRACH) resource.

S102: A serving gateway (serving gateway, SGW) sends a downlink data indication (downlink data notification) to a mobility management entity (mobility management entity, MME).

S103: The MME sends an S1-paging message.

The MME sends the paging (paging) message to the eNB through an S1 interface. The paging message includes a serving-temporary mobile subscriber identity (serving - temporary mobile subscriber identity, S-TMSI) and an EDT indication (indication) of UE to be paged, and the EDT indication is used to indicate the UE to receive data by using the EDT technology.

S104: The eNB sends the paging message to the UE.

The paging message carries the S-TMSI and the EDT indication that are carried in the S1-paging message received by the eNB from the MME.

S105: The UE sends a preamble (preamble) to the eNB.

Specifically, after the UE determines that the paging message is for the UE, the UE determines to initiate an EDT procedure. The UE determines, based on the PRACH resource in the EDT configuration information sent by the eNB, a preamble corresponding to the PRACH resource, and sends the preamble to the eNB.

S106: The eNB sends a random access response (random access response, RAR) message to the UE.

The RAR carries resource indication information used for uplink data transmission, for example, an uplink scheduling grant (UL grant).

S107: The UE sends an RRC early data transmission request (early data request) to the eNB.

The RRC early data request carries the S-TMSI, a connection establishment cause (estab cause), and a non-access stratum packet data unit (non-access stratum protocol data unit, NAS PDU). The NAS PDU is data corresponding to the paging message. The connection establishment cause may be indicated as mobile originated (mobile originate, MO)-EDT (that is, EDT initiated by the UE, or referred to as uplink EDT), or mobile terminated (mobile terminate, MT)-EDT (that is, EDT initiated by a network, or referred to as downlink EDT).

The UE sends the RRC early data request by using a resource indicated by the resource indication information that is carried in the RAR and that is used for uplink data transmission. The RRC early data request may be understood as a third message (message <NUM>, MSG3) in a random access process.

S108: The eNB sends an RRC early data transmission complete message (RRC early data complete) to the UE.

Specifically, after the eNB receives the MSG3 carrying the NAS PDU, the eNB sends the NAS PDU to the MME. After the MME receives the NAS PDU, the MME sends downlink data to the eNB, so that the eNB sends the received downlink data to the UE.

The RRC early data complete includes the downlink data. The RRC early data complete may be understood as a fourth message (message <NUM>, MSG4) in the random access process.

It can be learned that in the foregoing process, the downlink data is carried when the MSG4 is sent to the terminal device, and before the downlink data is sent, other signaling exists, causing a data transmission delay. Therefore, how to reduce the data transmission delay in the EDT technology is a technical problem to be urgently resolved currently.

In view of this, an embodiment of this application provides a data transmission method. In the method, if downlink data needs to be sent to a terminal device, an access network device may first send a paging message to the terminal device. After receiving the paging message, the terminal device determines, based on a first indication included in the paging message, a random access preamble used to initiate EDT, and sends the random access preamble to the access network device. After receiving the random access preamble, the access network device sends a response message to the terminal device, where the response message includes the downlink data and one or more of a timing advance TA, an uplink grant UL-Grant, a temporary cell radio network temporary identity TC-RNTI, or a logical channel identifier LCID.

In the foregoing technical solution, the response message that carries the downlink data and that is sent by the access network device to the terminal device may be understood as a second message (message <NUM>, MSG2) in a random access process. In other words, in this embodiment of this application, the downlink data is sent to the terminal device by using the MSG2, so that the terminal device receives the downlink data as early as possible, thereby reducing a data transmission delay.

The following describes an application scenario of the embodiments of this application.

<FIG> is a schematic diagram of a specific communication system architecture to which an embodiment of this application is applicable. The communication system architecture shown in <FIG> includes two parts: a radio access network and a core network. The radio access network is an evolved universal terrestrial radio access network (evolved universal terrestrial radio access network, E-UTRAN), and is configured to implement a function related to radio access. The core network includes an MME, an SGW, a packet data network gateway (packet data network gateway, PGW), and the like. The MME is mainly responsible for mobility management and session management on a control plane. The SGW is a user plane function entity, and routes and forwards packet data. The PGW is a gateway connected to an external data network. In actual network deployment, the S-GW and the P-GW may alternatively be deployed together, and may be collectively referred to as a gateway. UE may access an external PDN by establishing a connection from the UE to the E-UTRAN, then to the SGW, then to the PGW, and then to the packet data network (PDN).

<FIG> is a schematic diagram of another specific communication system architecture to which an embodiment of this application is applicable. The communication system architecture shown in <FIG> is also divided into two parts: a radio access network and a core network. The radio access network is a next generation radio access network (next generation radio access networks, NG-RAN), and is configured to implement a function related to radio access. The core network includes an access and mobility management function (core access and mobility management function, AMF) network element, a session management function (session management function, SMF) network element, a user plane function (user plane function, UPF) network element, and the like. The AMF network element is mainly responsible for mobility management. The AMF network element may also be referred to as an AMF device or an AMF entity. The SMF network element is mainly responsible for session management. The SMF network element may also be referred to as an SMF device or an SMF entity. The UPF is mainly responsible for processing, for example, forwarding, a packet of a user. UE may access a DN by establishing a session from the UE, to the NG-RAN, then to the UPF, and then to the data network (data network, DN).

It should be understood that, the communication system architectures provided in the embodiments of this application may be used for a <NUM> system, a long term evolution-advanced (advanced long term evolution, LTE-A) system, a worldwide interoperability for microwave access (worldwide interoperability for microwave access, WiMAX) system, a wireless local area network (wireless local area networks, WLAN) system, or the like.

In addition, the communication system architectures are further applicable to a future-oriented communication technology. The communication system architectures described in the embodiments of this application are intended to describe the technical solutions in the embodiments of this application more clearly, and constitute no limitation on the technical solutions provided in the embodiments of this application. A person of ordinary skill in the art may learn that, with evolution of network architectures, the technical solutions provided in the embodiments of this application are also applicable to a similar technical problem.

The following describes, with reference to the accompanying drawings, the technical solutions provided in the embodiments of this application.

An embodiment of this application provides a data transmission method. <FIG> is a flowchart of the method.

It should be noted that, when the method is used in a communication system shown in <FIG>, an access network device described below may be an access network device in the communication system architecture shown in <FIG>, for example, may be an eNB, a terminal device described below may be a terminal device in the communication system architecture shown in <FIG>, and a core network device described below may be a core network device in the communication system architecture shown in <FIG>, for example, may be an MME network element. When the method is used in a communication system shown in <FIG>, an access network device described below may be an access network device in the communication system architecture shown in <FIG>, for example, may be a gNB, a terminal device described below may be a terminal device in the communication system architecture shown in <FIG>, and a core network device described below may be a core network device in the communication system architecture shown in <FIG>, for example, may be an AMF network element.

For ease of description, an example in which the method is used in the communication system architecture shown in <FIG> is used.

S301: The access network device sends a paging message to the terminal device, and the terminal device receives the paging message.

In this embodiment of this application, the paging message includes a first indication, and the first indication is used to indicate a random access channel resource allocated by the access network device to the terminal device. The random access channel may be a physical random access channel (physical random access channel, PRACH), a machine type communication physical random access channel (MTC physical random access channel, MPRACH), a narrowband physical random access channel (narrowband physical random access channel, NPRACH), or an enhanced physical random access channel (enhanced physical random access channel, EPRACH). For ease of description, the following provides descriptions by using an example in which the random access channel is a PRACH.

A PRACH resource is a preamble (preamble) allocated to the terminal device, or a time-frequency resource that is allocated to the terminal device and used for random access, or a preamble allocated to the terminal and a time-frequency resource that is allocated to the terminal and used for random access.

In an example, the first indication may indicate a time-frequency resource on which a PRACH allocated to the terminal device is located. Alternatively, the access network device establishes mapping information of a PRACH resource for each terminal device, where the mapping information includes a time-frequency resource of each of all PRACH channels supported by the access network device. In this case, the first indication may indicate an index number, a number, or the like of the PRACH, so that the terminal device can determine, based on the index number or the number of the PRACH, a frequency domain position of the PRACH.

In another example, the terminal device and the access network device further store a correspondence between a PRACH resource and a preamble (preamble). In this case, the first indication may indicate an identifier of a preamble corresponding to a PRACH allocated to the terminal device, for example, an index number or a number of the preamble.

Certainly, the first indication may alternatively indicate, in another manner, the random access channel resource allocated to the terminal device. This is not limited herein.

In a possible implementation, the paging message may further include an EDT indication, and the first indication may be used to indicate that there is downlink data that needs to be delivered to the terminal device, or the first indication may be used to indicate the terminal device to trigger an EDT procedure.

S302: The terminal device sends, in response to the paging message, a random access preamble to the access network device, and the access network device receives the random access preamble.

In this embodiment of this application, the random access preamble sent by the terminal device corresponds to the first indication in the paging message. Specifically, after receiving the paging message, the terminal device first determines, based on the stored correspondence between a PRACH resource and a preamble, a preamble corresponding to a PRACH resource indicated by the paging message, and then sends the preamble to the access network device.

S303: The access network device sends, in response to the random access preamble, a response message to the terminal device, and the terminal device receives the response message.

In this embodiment of this application, the response message includes downlink data and one or more of a timing advance TA, an uplink grant UL-Grant, a temporary cell radio network temporary identity TC-RNTI, or a logical channel identifier LCID. It should be noted that in this case, the downlink data is carried in RRC signaling.

The following describes the response message. The response message may have but is not limited to the following two forms.

A first form is as follows:
The response message may be understood as a random access response (random access response, RAR) that carries the downlink data. In other words, a data field is added to a structure of a media access control (media access control, MAC) protocol data unit (protocol data unit, PDU) of an RAR in a current technology, and the downlink data is carried in the data field.

To clearly describe the response message in this embodiment of this application, the following describes a structure of a MAC PDU in a random access process.

<FIG> is a schematic diagram of an example of a MAC PDU in a random access process. The MAC PDU in the random access process includes three parts: a MAC header, a payload, and a possible padding.

The MAC header includes one or more MAC subheaders (subheader). <FIG> show two specific formats of the MAC subheader.

In <FIG>, the MAC subheader includes an E field, a T field, and a random access preamble identifier (random access preamble identifier, RAPID) field. In <FIG>, the MAC subheader includes an E field, a T field, two R fields, and a backoff indicator (backoff indicator, BI) field. The following describes the fields.

The E field is an extension field (extension field), and is used to indicate whether there is a MAC subheader subsequently, and a value of the field may be <NUM> or <NUM>. When the value of the field is <NUM>, it indicates that there is another MAC subheader following the MAC subheader. When the value of the field is <NUM>, it indicates that there is no other MAC subheader following the MAC subheader.

The T field is a type field (type field), and is used to indicate whether the MAC subheader carries the RAPID field or the BI field, and a value of the field may be <NUM> or <NUM>. When the value of the field is <NUM>, it indicates that the MAC subheader carries the RAPID field. When the value of the field is <NUM>, it indicates that the MAC subheader carries the BI field.

The R field is a reserved field and has a fixed value of <NUM>.

The BI field is used to indicate a maximum delay from time at which the RAR is not successfully received last time to time at which the preamble is resent next time, and uses a unit of ms. The BI field occupies four bits, and a value of the BI field may range from <NUM> to <NUM>.

The RAPID field occupies six bits, and a value of the field ranges from <NUM> to <NUM>.

The payload (payload) includes one or more RARs, and a specific quantity depends on a quantity of corresponding RAPID fields in the MAC subheader. If the MAC PDU is a response to two preambles, the MAC PDU includes two RARs. Refer to <FIG>. A format of the RAR is as follows:.

The RAR includes six bytes, and specifically includes an R field, a timing advance command (timing advance command) field, an uplink grant (UL grant) field, and a TC-RNTI field.

The timing advance command (timing advance command) field is used to indicate a TA value used by the terminal device to perform uplink synchronization, and usually occupies <NUM> bits.

The UL Grant field is used to indicate parameters such as a time-frequency resource and power control that are used by the terminal device to perform uplink transmission of an MSG3. The parameters are not described one by one herein. The UL Grant field usually occupies <NUM> bits.

The TC-RNTI field is used to indicate a TC-RNTI of the terminal device, and usually occupies <NUM> bits. When sending the MSG3, the terminal device scrambles the MSG3 by using the value.

The foregoing describes a format of the MAC PDU in the random access process in a current technology. In this embodiment of this application, to enable the MAC PDU of the response message to carry the downlink data, a manner used is as follows: A format of the MAC subheader in the MAC PDU in the random access process in the current technology is still used, and a data field is added to the RAR in the payload. <FIG> and <FIG> are each a schematic diagram of a format of an RAR included in a payload of a response message according to an embodiment of this application. In the RAR shown in <FIG>, an R field, an F field, an LCID field, an L field, and a data (data) field are added to the RAR. It is different from a format of the RAR shown in <FIG> that, the RAR shown in <FIG> includes two L fields.

The following describes the newly added fields in <FIG> and <FIG>.

LCID: a logical channel ID field, identifying a logical channel corresponding to the RAR or a type or a padding of the RAR. The LCID field may occupy six bits.

L: a length field, indicating a length of the data field. The L field may occupy eight bits.

F: a format field, indicating a length of the length field (L field). For example, whether the L field is eight bits or <NUM> bits may be indicated, and the F field may occupy one bit.

The newly added R field is a reserved field.

It should be noted that, if the LCID field indicates a common control channel (common control channel, CCCH), the L field may be omitted.

To enable a terminal device to learn, as soon as possible, whether a response message used by an access network device to respond to a preamble of the terminal device includes downlink data, the RAR may include a first field, where the first field is used to indicate that the RAR carries the downlink data.

For example, in each of subheaders shown in <FIG>, the first R field is used to indicate whether the RAR includes the downlink data. Refer to <FIG>. An R field used to indicate whether the RAR includes the downlink data is marked as an R1 field, and the other R field in the RAR is marked as an R2 field, that is, the R2 field is a reserved field. When a value of the R1 field is <NUM>, it may indicate that the RAR does not include the downlink data, that is, the RAR is an MSG2 in a current technology. When a value of the R1 field is <NUM>, it may indicate that the RAR includes the downlink data. Certainly, a value and specific indication content of the R1 field may be set based on a use requirement. This is not limited herein.

A second form is as follows:
The response message is different from an RAR in a current technology. The response message uses a new MAC PDU structure, and the new MAC PDU structure includes a data field carrying the downlink data. In other words, in this case, the response message is not an RAR in a random access process, or may be understood as a MAC PDU used for data transmission.

To clearly describe the response message in this embodiment of this application, the following describes a structure of a MAC PDU in a non-random access process in a current technology.

<FIG> shows an example of a structure of a MAC PDU in a non-random access process in a current technology. As shown in <FIG>, one MAC PDU includes a plurality of MAC sub protocol data units (subPDU). One MAC subPDU may include the following three cases:.

In this case, a subheader format of the MAC subPDU includes three cases shown in <FIG>. The subheader format shown in <FIG> includes an R field, an F field, an LCID field, and an L field. The subheader format shown in <FIG> includes an R field, an F field, an LCID field, and two L fields. The subheader format shown in <FIG> includes an R field, an F field, and an LCID field. The subheader format shown in <FIG> is used for a MAC CE of a definite size, for a padding, and for a data packet whose transmission is performed on a common control channel (common control channel, CCCH). The following describes the fields included in a subheader of the MAC subPDU.

LCID: a logical channel ID field, identifying a logical channel corresponding to the MAC subPDU or a type or a padding of the MAC CE. The LCID field may occupy six bits.

L: a length field, indicating a quantity of bytes of a MAC SDU in the MAC subPDU. The L field may occupy eight bits.

F: a format field, indicating a length of the length field. For example, whether the L field is eight bits or <NUM> bits may be indicated, and the F field may occupy one bit.

In this case, a new MAC subheader is designed, so that the MAC PDU shown in <FIG> can be used for transmission of downlink data. <FIG> is a schematic diagram of an example of a new MAC subheader according to an embodiment of this application.

In <FIG>, there is an R field, an F field, an LCID field, a TA field, a UL grant field, a TC-RNTI field, an L field, and a data (data) field. The L field is used to indicate a length of the data field. Meanings of the other fields are the same as corresponding content in the foregoing, and details are not described herein again.

It should be noted that, if the LCID field indicates a CCCH, the L field may be omitted.

In addition, it should be noted that a form of a response message used by the access network device may be pre-agreed on by the terminal device and the access network device, or may be indicated by the access network device. This is not limited herein. When the access network device sends a response message in the second form to the terminal device, the PRACH resource indicated in the paging message in step S301 is dedicated to the terminal device, and cannot be shared with another terminal device.

In this embodiment of this application, the response message is sent after the terminal device sends the preamble, and if the access network device fails to receive the preamble sent by the terminal device, the access network device does not send the response message to the terminal device. Therefore, from this perspective, the response message may be further used to indicate that the access network device successfully receives the preamble sent by the terminal device. In other words, the response message is an acknowledgement (acknowledge, ACK) message of the preamble. In this way, this can avoid a problem in the current technology that the downlink data fails to be received because the terminal device cannot learn whether the access network device successfully receives the preamble.

Before the access network device sends the downlink data to the terminal device by using the response message, the access network device may obtain the downlink data in manners that are, but not limited to, the following manners:.

In the manner <NUM>, when the access network device fails to obtain the downlink data from the core network device, that is, does not successfully obtain the downlink data from the core network device, the response message in step S303 does not carry the downlink data, that is, the response message in step S303 is the RAR in the random access process, and the response message carries an RRC connection setup (RRC connection setup) message in a field carrying the downlink data, so that when the terminal device determines that the response message is the RAR, the terminal device establishes an RRC connection based on the RAR. In this case, one piece of indication information may be used to indicate that the RAR carries the RRC connection setup message. For example, the indication may be performed by using one bit in a MAC PDU of the RAR, or may be implicitly performed by using an LCID, or may be performed by using RRC layer indication information.

It can be learned from the foregoing technical solution that the access network device may send the downlink data to the terminal device by using the MSG2, so that the terminal device receives the downlink data as early as possible, to reduce a data transmission delay. In addition, the access network device includes the TC-RNTI in the response message, that is, the TC-RNTI does not need to be carried in the paging message, so that more bits in the paging message are used to indicate a paging capacity. In this way, the paging capacity of the paging message can be increased.

Refer to <FIG>. Based on the embodiment shown in <FIG>, the following describes an example of triggering early data transmission of downlink data by a core network device. It should be understood that the example in <FIG> is specifically used in a <NUM> system architecture, and this embodiment of this application may be further used in another system architecture. This is not limited in this application.

Step <NUM>: A P-GW network element sends a downlink data arrival indication to an S-GW network element, where the downlink data arrival indication is used to indicate that downlink data (which may also be referred to as terminal data (MT data)) of UE arrives, and transmits the MT data to the S-GW network element.

Step <NUM>: After receiving the downlink data arrival indication, the S-GW network element sends a downlink early data transmission request (which may be referred to as an MT-EDT request) to an MME network element.

Step <NUM>: After receiving the MT-EDT request, the MME network element acknowledges the MT-EDT request with the S-GW network element (that is, by using an MT-EDT acknowledgement message), and sends a paging message to one or more eNBs in a registration area of the UE, where the paging message includes a NAS PDU sending request generated by the MME network element through NAS encapsulation.

Step <NUM>: Each base station that receives the paging message first determines a random access resource for initiating this time of MT-EDT, and then initiates paging to UE in coverage of the base station, where the paging message carries an MT-EDT indication, and a random access configuration (for example, which may include a preamble and/or a PRACH resource).

In <FIG>, only one eNB is used as an example for description.

Step <NUM>: After receiving the paging message, the UE first determines whether the paging message includes an MT-EDT indication for the UE (for example, performs the determining by determining whether the MT-EDT includes a UE identity (identity, ID) of the UE), and if the paging message includes the MT-EDT indication, sends, on the PRACH resource carried in the paging message, the preamble carried in the paging message to the eNB.

Step <NUM>: After receiving the preamble of the UE, the eNB determines that the UE is UE paged by the eNB, and requests, from the MME network element, a NAS PDU that includes downlink data of the UE.

Step <NUM>: After receiving the request, the MME network element sends, to the eNB, the NAS PDU that includes the downlink data of the UE.

Step <NUM>: The eNB sends an MSG2 including the downlink data to the UE.

A specific format of the MSG2 is shown in step S303 shown in <FIG>, and details are not described herein again.

If the eNB fails to obtain the NAS PDU from the MME network element due to an error, the MSG2 does not carry the downlink data, and an RRC connection setup message is carried in a field that is in the MSG2 that should have been used to send the downlink data.

Step <NUM>: After successfully receiving the downlink data by using the MSG2, the UE sends, by using a TA in the MSG2, an ACK message on a resource indicated by UL-Grant.

If the MSG2 does not carry the downlink data, after receiving the MSG2, the UE establishes an RRC connection based on the RRC connection setup message carried in the MSG. The UE determines, based on the message carried in the MSG2, how to respond to the MSG2.

Step <NUM>: After receiving the ACK message sent by the UE, the eNB sends an MT-EDT acknowledgement message to the MME network element.

It should be noted that an EDT process shown in <FIG> is an example of a scenario in which a core network device triggers early data transmission of downlink data. In this embodiment of this application, a method of including the downlink data in the MSG2 is not limited to this scenario, and is also applicable to another scenario in which EDT is required.

In the foregoing embodiment, a technical effect of early data transmission is implemented by including the downlink data in the MSG2. Refer to <FIG>. The following describes another data transmission method according to an embodiment of this application.

Step S1201: An access network device sends a paging message to a terminal device, and the terminal device receives the paging message.

The paging message includes a first indication. Descriptions for the paging message and the first indication are similar to those in step S301, and details are not described herein again.

Step S1202: The terminal device sends, in response to the paging message, a random access preamble to the access network device, and the access network device receives the random access preamble.

The random access preamble corresponds to the first indication.

Step S1201 and step S1202 are similar to step S301 and step S302, and details are not described herein again.

Step S1203: The access network device sends, in response to the random access preamble, a random access response RAR to the terminal device, and the terminal device receives the random access response RAR.

In this embodiment of this application, the RAR includes a temporary cell radio network temporary identity TC-RNTI. A format of the RAR in this embodiment of this application is the same as a format of an RAR in a current technology.

After receiving the RAR, the terminal device needs to process a TC-RNTI field in the RAR to obtain a value of the TC-RNTI field. In this step, a TA field and a UL-Grant field may not need to be processed. However, in the current technology, when the terminal device performs random access in a contention manner, the TA field, the TC-RNTI field, and the UL-grant field need to be processed. When the terminal device performs random access in a non-contention manner, the TA field and the UL-grant field need to be processed. It can be learned that, compared with a method in the current technology, a processing amount of the terminal device can be reduced, and efficiency of early data transmission can be improved.

Step S1204: The access network device sends downlink data to the terminal device, and the terminal device receives the downlink data.

In this embodiment of this application, a manner in which the access network device sends the downlink data to the terminal device may include but is not limited to the following manner:.

The access network device first sends, to the terminal device, a second indication used to indicate a location of a time-frequency resource of the downlink data. For example, the second indication may be sent on a physical downlink control channel (physical downlink control channel, PDCCH). It should be noted that the second indication is an indication scrambled by the access network device by using the TC-RNTI carried in step S1203. Therefore, the terminal device may blindly detect the downlink control channel by using the TC-RNTI carried in step S1203. After detecting the first indication, the terminal device determines, based on the first indication, a time-frequency resource on which the access network device sends the downlink data, and then receives the downlink data on the corresponding time-frequency resource.

Before the access network device sends the downlink data to the terminal device, a manner of obtaining the downlink data is similar to corresponding content in the embodiment shown in <FIG>, and details are not described herein again.

When the access network device cannot successfully obtain the downlink data, the access network device may also include an RRC connection setup message in the RAR, to trigger the terminal device to establish an RRC connection. A specific manner is similar to corresponding content in the embodiment shown in <FIG>, and details are not described herein again.

It can be learned from the foregoing technical solution that, the access network device includes the TC-RNTI in the RAR, that is, the TC-RNTI does not need to be carried in the paging message, so that more bits in the paging message are used to indicate a paging capacity. In this way, the paging capacity of the paging message can be increased. In addition, because the RAR is sent after the terminal device sends the preamble, from this perspective, the RAR may be further used to indicate that the access network device successfully receives the preamble sent by the terminal device. In this way, a problem in the current technology that the downlink data fails to be received because the terminal device cannot learn whether the access network device successfully receives the preamble can be avoided.

Step <NUM>: After receiving the MT-EDT request, the MME network element acknowledges the MT-EDT request with the S-GW network element, and sends a paging message to one or more eNBs in a registration area of the UE, where the paging message includes a NAS PDU sending request generated by the MME network element through NAS encapsulation.

Step <NUM>: After receiving the paging message, the UE first determines whether the paging message includes an MT-EDT indication for the UE, and if the paging message includes the MT-EDT indication for the UE, sends, on the PRACH resource carried in the paging message, the preamble carried in the paging message to the eNB.

Step <NUM>: After receiving the preamble of the UE, the eNB determines that the UE is UE paged by the eNB, and sends an RAR to the UE, where the RAR includes a TA field, a UL-Grant field, and a TC-RNTI field (that is, an RAR in a random access process in a current technology). In this process, the UE needs to process the TC-RNTI field, and does not need to process the TA and UL-Grant fields.

Step <NUM>: The eNB requests, from the MME network element, a NAS PDU that includes the downlink data of the UE.

In this embodiment of this application, a sequence of performing step <NUM> and step <NUM> is not limited. Step <NUM> and step S1306 may be simultaneously performed, or step <NUM> may be performed first and then step <NUM> is performed.

Step <NUM>: The UE uses the TC-RNTI to blindly detect a PDCCH, to receive the downlink data.

Step <NUM>: The eNB sends the downlink data of the UE (where the downlink data is the MT data) by using the TC-RNTI.

A specific implementation of step <NUM> is similar to that of step S1204, and details are not described herein again.

Step <NUM>: After receiving the downlink data, the UE determines values of the TA field and the UL-Grant field in the RAR in step <NUM>, and sends an ACK message on a resource indicated by UL-Grant.

If the eNB fails to obtain the NAS PDU from the MME network element due to an error, the eNB does not perform step <NUM> and another subsequent step.

It should be noted that an EDT process shown in <FIG> is an example of a scenario in which a core network device triggers early data transmission of downlink data. A method in this embodiment of this application is not limited to this scenario, and is also applicable to another scenario in which EDT is required.

In the embodiment shown in <FIG>, a method for performing early data transmission by using a TC-RNTI carried in an RAR is described. Refer to <FIG>. The following describes another data transmission method according to an embodiment of this application.

Step S1401: An access network device sends a paging message to a terminal device, and the terminal device receives the paging message.

Step S1402: The terminal device sends, in response to the paging message, a random access preamble to the access network device, and the access network device receives the random access preamble.

Step S1401 and step S1402 are similar to step S301 and step S302, and details are not described herein again.

Step S1403: The access network device sends, in response to the random access preamble, a random access response RAR to the terminal device, and the terminal device receives the random access response RAR.

In this embodiment of this application, the RAR includes a downlink assignment DL-assignment. Specifically, the RAR includes a second field used to indicate a UL-grant, where the second field may also be referred to as a UL-grant field. In this case, the access network device may include the DL-assignment in the UL-grant field. In other words, content that should have been indicated by the UL-grant field is a value of the UL-grant. In this embodiment of this application, the content indicated by the UL-grant field is a value of the DL-assignment.

To implement the foregoing function, the access network device may send indication information to the terminal device, to notify the terminal device of a meaning of the content indicated by the UL-grant field. For example, the UL-grant field indicates the value of the DL-assignment. Alternatively, the access network device and the terminal device may agree on a meaning of the content indicated by the UL-grant field. Alternatively, the access network device may include indication information in the RAR, and indicate, by using the indication information, a meaning of the content indicated by the UL-grant field. This is not limited herein.

Because the UL grant field in the RAR is used to indicate the value of the DL assignment, the terminal device may receive the downlink data based on a location indicated by the DL assignment. In this way, duration of blindly detecting a PDCCH by the terminal device can be reduced, and data transmission efficiency can be improved.

In this embodiment of this application, the RAR further includes a TA field, a temporary cell radio network temporary identity TC-RNTI, and the like. In this process, the terminal device needs to process the TC-RNTI field and the field indicating the value of the DL assignment (which is actually the UL grant field).

Step S1404: The access network device sends the downlink data to the terminal device on a time-frequency resource indicated by the DL-assignment, and the terminal device receives the downlink data on the time-frequency resource indicated by the DL-assignment.

A manner in which the access network device sends the downlink data is similar to that in step S1204, and details are not described herein again.

In the foregoing embodiments provided in this application, the methods provided in the embodiments of this application are separately described from perspectives of an access network device, a terminal device, and interaction between the two. To implement the functions in the methods provided in the embodiments of this application, the access network device and the terminal device may each include a hardware structure and/or a software module, and implement the functions in a form of the hardware structure, the software module, or a combination of the hardware structure and the software module. Whether a function in the foregoing functions is performed by the hardware structure, the software module, or the combination of the hardware structure and the software module depends on particular applications and design constraints of the technical solutions.

<FIG> is a schematic structural diagram of a data transmission apparatus <NUM>. The data transmission apparatus <NUM> may be an access network device, and can implement a function of the access network device in the methods provided in the embodiments of this application. The data transmission apparatus <NUM> may alternatively be an apparatus that can support the access network device in implementing a function of the access network device in the methods provided in the embodiments of this application. The data transmission apparatus <NUM> may be a hardware structure, a software module, or a combination of a hardware structure and a software module. The data transmission apparatus <NUM> may be implemented by a chip system. In the embodiments of this application, the chip system may include a chip, or may include a chip and another discrete component.

The data transmission apparatus <NUM> may include a processing module <NUM> and a communication module <NUM>.

The processing module <NUM> may be configured to generate information sent by the communication module <NUM> in <FIG> or <FIG> to <FIG>, or configured to perform step S1104 in the embodiment shown in <FIG>, or configured to perform step S1304 in the embodiment shown in <FIG>, and/or configured to support another process of the technology described in this specification.

The communication module <NUM> is used by the data transmission apparatus <NUM> to communicate with another module, and may be a circuit, a component, an interface, a bus, a software module, a transceiver, or any other apparatus that can implement communication.

The communication module <NUM> may be configured to perform step S301 to step S303 in the embodiment shown in <FIG>, or may be configured to perform step S1103 to step S1110 in the embodiment shown in <FIG>, or may be configured to perform step S1201 to step S1204 in the embodiment shown in <FIG>, or may be configured to perform step S1303 to step S1308 and step S1310 to step S1312 in the embodiment shown in <FIG>, or configured to perform step S1401 to step S1404 in the embodiment shown in <FIG>, and/or configured to support another process of the technology described in this specification.

All related content of the steps in the foregoing method embodiments may be cited in function descriptions of corresponding functional modules.

<FIG> is a schematic structural diagram of a data transmission apparatus <NUM>. The data transmission apparatus <NUM> may be a terminal device, and can implement a function of the terminal device in the methods provided in the embodiments of this application. The data transmission apparatus <NUM> may alternatively be an apparatus that can support the terminal device in implementing a function of the terminal device in the methods provided in the embodiments of this application. The data transmission apparatus <NUM> may be a hardware structure, a software module, or a combination of a hardware structure and a software module. The data transmission apparatus <NUM> may be implemented by a chip system. In the embodiments of this application, the chip system may include a chip, or may include a chip and another discrete component.

The processing module <NUM> may be configured to generate information sent by the communication module <NUM> in <FIG> or <FIG> to <FIG>, or configured to perform step S1309 in the embodiment shown in <FIG>, and/or configured to support another process of the technology described in this specification.

The communication module <NUM> may be configured to perform step S301 to step S303 in the embodiment shown in <FIG>, or may be configured to perform step S1104, step S1105, step S1108, and step S1109 in the embodiment shown in <FIG>, or may be configured to perform step S1201 to step S1204 in the embodiment shown in <FIG>, or may be configured to perform step S1304 to step S1306, step S1310, and step S1311 in the embodiment shown in <FIG>, or configured to perform step S1401 to step S1404 in the embodiment shown in <FIG>, and/or configured to support another process of the technology described in this specification. The communication module <NUM> is used by the data transmission apparatus <NUM> to communicate with another module, and may be a circuit, a component, an interface, a bus, a software module, a transceiver, or any other apparatus that can implement communication.

Division into modules in the embodiments of this application is an example, is only logical function division, and may be other division during actual implementation. In addition, functional modules in the embodiments of this application may be integrated into one processor, or may exist alone physically, or two or more modules may be integrated into one module. The integrated module may be implemented in a form of hardware, or may be implemented in a form of a software function module.

<FIG> shows a data transmission apparatus <NUM> according to an embodiment of this application. The data transmission apparatus <NUM> may be the terminal device in the embodiment shown in any one of <FIG> or <FIG> to <FIG>, and can implement a function of the terminal device in the methods provided in the embodiments of this application. The data transmission apparatus <NUM> may alternatively be an apparatus that can support the terminal device in implementing a function of the terminal device in the methods provided in the embodiments of this application. The data transmission apparatus <NUM> may be a chip system. In the embodiments of this application, the chip system may include a chip, or may include a chip and another discrete component.

In hardware implementation, the communication module <NUM> may be a transceiver, and the transceiver is integrated into the data transmission apparatus <NUM> to form a communication interface <NUM>.

The data transmission apparatus <NUM> includes at least one processor <NUM>, configured to implement or support the data transmission apparatus <NUM> in implementing a function of the access network device in the methods provided in the embodiments of this application. For example, the processor <NUM> may use a TC-RNTI to blindly detect a PDCCH. For details, refer to detailed descriptions in the method examples.

The data transmission apparatus <NUM> may further include at least one memory <NUM>, configured to store program instructions and/or data. The coupling in this embodiment of this application is an indirect coupling or a communication connection between apparatuses, units, or modules, may be in an electrical form, a mechanical form, or another form, and is used for information exchange between the apparatuses, the units, or the modules. The processor <NUM> may cooperate with the memory <NUM>. The processor <NUM> may execute the program instructions stored in the memory <NUM>. At least one of the at least one memory may be included in the processor.

The data transmission apparatus <NUM> may further include a communication interface <NUM>, configured to communicate with another device through a transmission medium, so that an apparatus used in the data transmission apparatus <NUM> can communicate with the another device. For example, the another device may be an access network device. The processor <NUM> may send and receive data through the communication interface <NUM>. The communication interface <NUM> may be specifically a transceiver.

A specific connection medium between the communication interface <NUM>, the processor <NUM>, and the memory <NUM> is not limited in this embodiment of this application. In this embodiment of this application, the memory <NUM>, the processor <NUM>, and the communication interface <NUM> are connected through a bus <NUM> in <FIG>, and the bus is represented by a thick line in <FIG>. A connection manner between other components is merely schematically described, and is not limited thereto. The bus may be classified into an address bus, a data bus, a control bus, and the like. For ease of representation, only one thick line is used to represent the bus in <FIG>, but this does not mean that there is only one bus or only one type of bus.

In this embodiment of this application, 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 transistor logic device, or a discrete hardware component, and may implement or perform the methods, steps, and logical block diagrams disclosed in the embodiments of this application. 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 this application may be directly performed by a hardware processor, or may be performed by a combination of hardware and software modules in the processor.

In this embodiment of this application, the memory <NUM> may be a non-volatile memory, such as a hard disk drive (hard disk drive, HDD) or a solid-state drive (solid-state drive, SSD), or may be a volatile memory (volatile memory), such as a random access memory (random-access memory, RAM). The memory is any other medium that can carry or store expected program code in a form of an instruction structure or a data structure and that can be accessed by a computer, but is not limited thereto. The memory in the embodiments of this application may alternatively be a circuit or any other apparatus that can implement a storage function, and is configured to store the program instructions and/or the data.

<FIG> shows a data transmission apparatus <NUM> according to an embodiment of this application. The data transmission apparatus <NUM> may be an access network device, and can implement a function of the access network device in the methods provided in the embodiments of this application. The data transmission apparatus <NUM> may alternatively be an apparatus that can support the access network device in implementing a function of the access network device in the methods provided in the embodiments of this application. The data transmission apparatus <NUM> may be a chip system. In the embodiments of this application, the chip system may include a chip, or may include a chip and another discrete component.

The data transmission apparatus <NUM> includes at least one processor <NUM>, configured to implement or support the data transmission apparatus <NUM> in implementing a function of the access network device in the methods provided in the embodiments of this application. For example, the processor <NUM> may determine a PRACH resource. For details, refer to detailed descriptions in the method examples.

The data transmission apparatus <NUM> may further include a communication interface <NUM>, configured to communicate with another device through a transmission medium, so that an apparatus used in the apparatus <NUM> can communicate with the another device. For example, the another device may be a terminal. The processor <NUM> may send and receive data through the communication interface <NUM>. The communication interface <NUM> may be specifically a transceiver.

An embodiment of this application further provides a data transmission apparatus. The data transmission apparatus may be a terminal or a circuit. The data transmission apparatus may be configured to perform an action performed by the terminal device in the foregoing method embodiments.

When the data transmission apparatus is a terminal device, <FIG> is a simplified schematic structural diagram of the terminal device. For ease of understanding and illustration, an example in which the terminal device is a mobile phone is used in <FIG>. As shown in <FIG>, the terminal device includes a processor, a memory, a radio frequency circuit, an antenna, and an input/output apparatus. The processor is mainly configured to: process a communication protocol and communication data, control the terminal device, execute a software program, process data of the software program, and the like. The memory is configured to store the software program and the data. The radio frequency circuit is mainly configured to: perform conversion between a baseband signal and a radio frequency signal, and process the radio frequency signal. The antenna is mainly configured to send/receive a radio frequency signal in a form of an electromagnetic wave. The input/output apparatus, such as a touchscreen, a display screen, or a keyboard, is mainly configured to: receive data entered by a user, and output data to the user. It should be noted that terminal devices of some types may have no input/output apparatus.

When needing to send data, after performing baseband processing on the to-be-sent data, the processor outputs a baseband signal to the radio frequency circuit; and the radio frequency circuit performs radio frequency processing on the baseband signal and then sends the radio frequency signal to outside in a form of an electromagnetic wave by using the antenna. When data is sent to the terminal device, the radio frequency circuit receives the radio frequency signal by using the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor, and the processor converts the baseband signal into data and processes the data. For ease of description, only one memory and one processor are shown in <FIG>. In an actual terminal device product, there may be one or more processors and one or more memories. The memory may also be referred to as a storage medium, a storage device, or the like. The memory may be disposed independent of the processor, or may be integrated with the processor. This is not limited in the embodiments of this application.

In this embodiment of this application, the antenna and the radio frequency circuit that have receiving and sending functions may be considered as a transceiver unit of the terminal device, and the processor that has a processing function may be considered as a processing unit of the terminal device. As shown in <FIG>, the terminal device includes a transceiver unit <NUM> and a processing unit <NUM>. The transceiver unit may also be referred to as a transceiver, a transceiver machine, a transceiver apparatus, or the like. The processing unit may also be referred to as a processor, a processing board, a processing module, a processing apparatus, or the like. Optionally, a component that is in the transceiver unit <NUM> and that is configured to implement a receiving function may be considered as a receiving unit, and a component that is in the transceiver unit <NUM> and that is configured to implement a sending function may be considered as a sending unit. In other words, the transceiver unit <NUM> includes the receiving unit and the sending unit. The transceiver unit sometimes may also be referred to as a transceiver machine, a transceiver, a transceiver circuit, or the like. The receiving unit may also be sometimes referred to as a receiver machine, a receiver, a receiving circuit, or the like. The sending unit may also be sometimes referred to as a transmitter machine, a transmitter, a transmitting circuit, or the like.

It should be understood that the transceiver unit <NUM> is configured to perform a sending operation and a receiving operation on a terminal device side in the foregoing method embodiments, and the processing unit <NUM> is configured to perform an operation other than the receiving operation and the sending operation of the terminal device in the foregoing method embodiments.

For example, in an implementation, the transceiver unit <NUM> is configured to perform step S301 to step S303 in the embodiment shown in <FIG>, or is configured to perform step S1104, step S1105, step S1108, and step S1109 in the embodiment shown in <FIG>, or is configured to perform step S1201 to step S1204 in the embodiment shown in <FIG>, or is configured to perform step S1304 to step S1306, step S1310, and step S1311 in the embodiment shown in <FIG>, or is configured to perform receiving and sending operations on the terminal device side in step S1401 to step S1404 in the embodiment shown in <FIG>, and/or the transceiver unit <NUM> is further configured to perform other receiving and sending steps on the terminal device side in the embodiments of this application. The processing unit <NUM> is configured to generate information sent by the communication module <NUM> in <FIG> or <FIG> to <FIG>, or configured to perform step S1309 in the embodiment shown in <FIG>, and/or the processing unit <NUM> is further configured to perform another processing step on the terminal device side in the embodiments of this application.

When the data transmission apparatus is a chip, the chip includes a transceiver unit and a processing unit. The transceiver unit may be an input/output circuit or a communication interface. The processing unit may be a processor, a microprocessor, or an integrated circuit, integrated on the chip.

When the data transmission apparatus in this embodiment is a terminal device, refer to a device shown in <FIG>. In an example, the device can implement a function similar to a function of the processor <NUM> in <FIG>. In <FIG>, the device includes a processor <NUM>, a data sending processor <NUM>, and a data receiving processor <NUM>. The processing module <NUM> in the foregoing embodiment may be the processor <NUM> in <FIG>, and implements a corresponding function. The transceiver module <NUM> in the foregoing embodiment may be the data sending processor <NUM> and/or the data receiving processor <NUM> in <FIG>. Although <FIG> shows a channel encoder and a channel decoder, it may be understood that these modules do not constitute a limitation on this embodiment and are merely examples.

<FIG> shows another form of this embodiment. A data transmission apparatus <NUM> includes modules such as a modulation subsystem, a central processing subsystem, and a peripheral subsystem. The data transmission apparatus in this embodiment may be used as the modulation subsystem in the data transmission apparatus. Specifically, the modulation subsystem may include a processor <NUM> and an interface <NUM>. The processor <NUM> implements the functions of the processing module <NUM>, and the interface <NUM> implements the functions of the communication module <NUM>. In another variation, the modulation subsystem includes a memory <NUM>, the processor <NUM>, and a program that is stored in the memory <NUM> and that can be run on the processor. When executing the program, the processor <NUM> implements a method on the terminal device side in the foregoing method embodiments. It should be noted that the memory <NUM> may be non-volatile or volatile. The memory <NUM> may be located in the modulation subsystem, or may be located in a processing apparatus <NUM>, provided that the memory <NUM> can be connected to the processor <NUM>.

In another form of this embodiment, a computer-readable storage medium is provided. The computer-readable storage medium stores instructions. When the instructions are executed, the method on the terminal device side in the foregoing method embodiments is performed.

In another form of this embodiment, a computer program product that includes instructions is provided. When the instructions are executed, the method on the terminal device side in the foregoing method embodiments is performed.

When the apparatus in this embodiment is an access network device, the access network device may be shown in <FIG>. An apparatus <NUM> includes one or more radio frequency units, such as a remote radio unit (remote radio unit, RRU) <NUM> and one or more baseband units (baseband unit, BBU) (which may also be referred to as digital units, digital units, DUs) <NUM>. The RRU <NUM> may be referred to as a communication module, and corresponds to the communication module <NUM> in <FIG>. Optionally, the communication module may also be referred to as a transceiver machine, a transceiver circuit, a transceiver, or the like, and may include at least one antenna <NUM> and a radio frequency unit <NUM>. The RRU <NUM> part is mainly configured to: receive and send a radio frequency signal, and perform conversion between the radio frequency signal and a baseband signal, for example, is configured to send indication information to the terminal device. The BBU <NUM> part is mainly configured to: perform baseband processing, control the base station, and the like. The RRU <NUM> and the BBU <NUM> may be physically disposed together, or may be physically separated, that is, in a distributed base station.

The BBU <NUM> is a control center of the base station, and may also be referred to as a processing module. The BBU <NUM> may correspond to the processing module <NUM> in <FIG>, and is mainly configured to implement a baseband processing function such as channel coding, multiplexing, modulation, or spreading. For example, the BBU (the processing module) may be configured to control the base station to perform an operation procedure related to a network device in the foregoing method embodiments, for example, generate the foregoing indication information.

In an example, the BBU <NUM> may include one or more boards, and a plurality of boards may jointly support a radio access network (for example, an LTE network) having a single access standard, or may separately support radio access networks (for example, an LTE network, a <NUM> network, or another network) having different access standards. The BBU <NUM> further includes a memory <NUM> and a processor <NUM>. The memory <NUM> is configured to store necessary instructions and data. The processor <NUM> is configured to control the base station to perform a necessary action, for example, is configured to control the base station to perform the operation procedure related to the network device in the foregoing method embodiments. The memory <NUM> and the processor <NUM> may serve the one or more boards. To be specific, a memory and a processor may be separately disposed on each board. Alternatively, a plurality of boards may share a same memory and a same processor. In addition, each board may be further provided with a necessary circuit.

An embodiment of this application further provides a computer-readable storage medium, including instructions. When the instructions are run on a computer, the computer is enabled to perform the method performed by the terminal device in the embodiment in any one of <FIG> or <FIG> to <FIG>.

An embodiment of this application further provides a computer-readable storage medium, including instructions. When the instructions are run on a computer, the computer is enabled to perform the method performed by the access network device in the embodiment in any one of <FIG> or <FIG> to <FIG>.

An embodiment of this application further provides a computer program product, including instructions. When the instructions are run on a computer, the computer is enabled to perform the method performed by the terminal device in the embodiment in any one of <FIG> or <FIG> to <FIG>.

An embodiment of this application further provides a computer program product, including instructions. When the instructions are run on a computer, the computer is enabled to perform the method performed by the access network device in the embodiment in any one of <FIG> or <FIG> to <FIG>.

An embodiment of this application provides a chip system. The chip system includes a processor, may further include a memory, and is configured to implement a function of the terminal device in the foregoing methods. The chip system may include a chip, or may include a chip and another discrete component.

An embodiment of this application provides a chip system. The chip system includes a processor, may further include a memory, and is configured to implement a function of the access network device in the foregoing methods. The chip system may include a chip, or may include a chip and another discrete component.

An embodiment of this application provides a system. The system includes the foregoing access network device or terminal device.

Claim 1:
A data transmission method, comprising:
sending (S301), by an access network device, a paging message to a terminal device, wherein the paging message comprises a first indication and does not comprise a temporary cell radio network temporary identity TC-RNTI;
receiving (S302), by the access network device, a random access preamble from the terminal device, wherein the random access preamble corresponds to the first indication; and
sending (S303), by the access network device in response to the random access preamble, a random access response message RAR to the terminal device, wherein the random access response message RAR comprises a first field and downlink data and a temporary cell radio network temporary identity TC-RNTI and wherein the first field indicates that the random access response message RAR carries the downlink data, and wherein the response message indicates that the access network device successfully receives the random access preamble.