CN110831252A

CN110831252A - Radio Resource Control (RRC) connection establishment method and related equipment

Info

Publication number: CN110831252A
Application number: CN201810914101.8A
Authority: CN
Inventors: 晋英豪; 张宏卓; 杨旭东; 谭巍
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-08-10
Filing date: 2018-08-10
Publication date: 2020-02-21
Anticipated expiration: 2038-08-10
Also published as: WO2020029747A1; CN110831252B

Abstract

The embodiment of the application discloses a method for establishing Radio Resource Control (RRC) connection and related equipment, comprising the following steps: a central unit of an access network receives a first message sent by a distributed unit of the access network, wherein the first message comprises first reason value information of an RRC connection establishment request sent by a user unit UE to the distributed unit; the central unit sends a second message to the distributed unit, the second message comprises an RRC connection establishment message and first indication information, and the first indication information is used for indicating the distributed unit to allow the UE to establish the RRC connection.

Description

Radio Resource Control (RRC) connection establishment method and related equipment

Technical Field

The present application relates to the field of wireless network technologies, and in particular, to a method for establishing a radio resource control RRC connection and related devices.

Background

For a base station in an access network, such as a 5G base station (gNB), the gNB may be split into two parts according to a protocol stack function: a Central Unit (CU) and a Distributed Unit (DU). The CU includes the main functions of the gNB, such as mobility management and Radio Resource Control (RRC) functions of the UE, and the DU includes the partial gNB functions other than the CU, such as a Medium Access Control (MAC) protocol stack function and a physical layer (PHY) protocol stack function. Under the network architecture, how to guarantee normal communication is a considerable problem.

Disclosure of Invention

The embodiment of the application provides a method for establishing radio resource control RRC connection, so as to guarantee normal communication.

In a first aspect, an embodiment of the present application provides a method for establishing a radio resource control RRC connection, including: a central unit of an access network firstly receives a first message sent by a distributed unit of the access network, wherein the first message comprises first reason value information of an RRC connection establishment request sent to the distributed unit by a user unit UE; and then sending a second message to the distributed unit, wherein the second message comprises an RRC connection establishment message and first indication information, and the first indication information is used for indicating the distributed unit to allow the UE to establish the RRC connection. And indicating the DU by the first indication information to allow the UE to access the network, so that the UE can access the network to ensure that the communication is normally carried out.

In one possible design, after receiving the first message sent by the DU, the CU determines to allow the UE to establish the RRC connection according to the first cause value information. So that the CU can determine whether to allow the UE to quickly access the network by judging the first cause value information.

In another possible design, the central unit sends a second message to the distributed units, including: and in the case that the central unit determines that the distributed unit rejects the access of the UE, the central unit sends a second message to the distributed unit. The CU may indicate to the DU that the UE is allowed to access the network by sending a second message in case the DU denies the UE access.

In another possible design, the CU decides to let the UE access the network again and does not accept the access control decision of the DU completely, so the CU generates an RRC connection setup message for the UE, which includes configuration information of the protocol stack of the SRB1 allocated by the CU for the UE, for example, configuration information of a higher layer protocol stack. The configuration information of the higher layer protocol stack may include PDCP configuration information. Thereby establishing the RRC connection after the UE receives the RRC connection setup message and accessing the network after completing the SRB1 configuration.

In one possible design, the first cause value information may be an emergency, a high priority access, or an access network notification area update, so that the UE can access the network in various scenarios.

In another possible design, the second message is a downlink RRC transfer message or a UE context setup request message.

In another possible design, the first indication information may be first cause value information, second cause value information, or indication value information.

In another possible design, the second message includes configuration information of a higher layer protocol stack of a signaling radio bearer allocated by the central unit to the UE. So that the UE can access the network after completing the SRB1 configuration according to the configuration information.

In another possible design, the first indication information is used to indicate that the DU allows the UE to establish the RRC connection. Specifically, the following cases may be included but not limited: the first indication information may indicate that the DU establishes an RRC connection for the UE; or indicating the DU to provide service for the UE; or indicating the DU to allow UE access; or indicating the DU to allow the UE to establish RRC connection; or suggesting that the DU allows the UE to establish RRC connection; or suggesting the DU to provide service for the UE; or instruct the CU to allow UE access; or instruct the CU to decide to provide service to the UE, etc. So that the DU can re-determine whether to allow the UE to access the network according to the first indication information.

In another possible design, the second cause value information may be generated from or related to the first cause value information in the first message.

In another possible design, the indicator value information may be a specific value, such as 0 or 1. For example, when the indication value information is 1, the DU is indicated to establish RRC connection for the UE; or indicating the DU to provide service for the UE; or indicating the DU to allow UE access; or indicating the DU to allow the UE to establish RRC connection; or suggesting that the DU allows the UE to establish RRC connection; or suggesting the DU to provide service for the UE; or instruct the CU to allow UE access; or instruct the CU to decide to provide service to the UE, etc. The DU may reject the RRC connection setup request of the UE when the indicator value information is 0 or there is no indicator value information. So that the DU can re-determine whether to allow the UE to access the network based on the indicator value information.

In another possible design, the indicator value information may also indicate that the RRC connection setup message included in the second message needs to be sent on SRB 1. The DU confirms that the CU allows the UE to access the network by indicating that the RRC connection establishment contained in the second message needs to be sent on SRB 1. So that the DU can re-determine whether to allow the UE to access the network based on the indicator value information.

In another possible design, after the DU receives the second message sent by the CU, the DU may still refuse to establish the RRC access network of the UE, e.g., still congested, and the service traffic is all in case of emergency calls. In this case, the CU may receive a third message sent by the DU, the third message including second indication information for indicating that the DU rejects the UE to establish the RRC connection. So that the CU can reconsider whether the UE is allowed to access the network.

In another possible design, the third message may also carry a reason why the DU rejects the UE to establish the RRC connection. So that the CU can reconsider whether the UE is allowed to access the network.

In a second aspect, an embodiment of the present application provides a radio resource control RRC connection establishment method, including: a central unit of an access network firstly receives a first message sent by a distributed unit of the access network, wherein the first message comprises first timer information, and the first timer information is used for indicating the time when the distributed unit generates a user unit UE to resend an RRC connection establishment request; then sending a second message to the distributed unit, wherein the second message comprises second timer information, and the second timer information is used for indicating the time for the UE to resend the RRC connection establishment request; wherein the second timer information is the same as the first timer information, or the second timer information is generated based on the first timer information. And after waiting for the time indicated by the second timer information, the UE can resend the RRC connection establishment request to access the network so as to guarantee that the communication is normally carried out.

In one possible design, in a case that the CU determines to reject the UE from establishing the RRC connection, the CU generates an RRC connection reject message including the second timer information. Therefore, the UE can resend the RRC connection establishment request to access the network when receiving the RRC connection rejection message so as to guarantee that the communication is normally carried out.

In another possible design, the CU confirms that the DU denies the UE access to the network, including: the acknowledgement is made by the first message. For example, the first message does not include the DU to CU RRC information, i.e., the CU may confirm that the DU denies the UE to access the network. Or the first message includes the first timer information, i.e. the CU can confirm that the DU denies the UE to access the network.

In a third aspect, an embodiment of the present application provides a method for establishing a radio resource control RRC connection, including: under the condition that a distributed unit of an access network rejects an RRC connection establishment request of a user Unit (UE), the distributed unit firstly sends a first message to a central unit of the access network, wherein the first message comprises first reason value information of the RRC connection establishment request; and then receiving a second message sent by the central unit, wherein the second message comprises an RRC connection establishment message and first indication information, and the first indication information is used for indicating that the distributed unit allows the UE to establish the RRC connection. And indicating the DU by the first indication information to allow the UE to access the network, so that the UE can access the network to ensure that the communication is normally carried out.

In one possible design, the distributed unit receives a second message sent by the central unit, and includes: and under the condition that the central unit determines that the distributed unit rejects the access of the UE, the distributed unit receives a second message sent by the central unit. The method realizes that whether the UE is allowed to access the network is determined again under the condition that the DU rejects the UE access.

In another possible design, after the distributed unit receives the second message sent by the central unit, the distributed unit sends an RRC connection setup message to the UE, where the RRC connection setup message includes configuration information of a protocol stack of a signaling radio bearer allocated by the central unit to the UE. Thereby establishing the RRC connection after the UE receives the RRC connection setup message and accessing the network after completing the SRB1 configuration.

In another possible design, the first cause value information may be an emergency, high priority access, or access network notification area update.

In another possible design, the second message includes configuration information of a higher layer protocol stack of a signaling radio bearer allocated by the central unit for the UE. So that the UE can access the network after completing the SRB1 configuration according to the configuration information.

In another possible design, the indicator value information may also indicate that the RRC connection setup message included in the second message needs to be sent on SRB 1. The DU considers the CU to allow the UE to access the network by indicating that the RRC connection setup contained in the second message needs to be sent on SRB 1. So that the DU can re-determine whether to allow the UE to access the network based on the indicator value information.

In another possible design, after the DU receives the second message sent by the CU, the DU may still refuse to establish the RRC access network of the UE, e.g., still congested, and the service traffic is all in case of emergency calls. In this case, the DU may send a third message to the CU, the third message including second indication information for indicating that the DU rejects the UE to establish the RRC connection.

In a fourth aspect, an embodiment of the present application provides a radio resource control RRC connection establishment method, including: a distributed unit of an access network firstly sends a first message to a central unit of the access network, wherein the first message comprises first timer information, and the first timer information is used for indicating the time when the distributed unit generates a user unit UE to resend an RRC connection establishment request; then receiving a second message sent by the central unit, wherein the second message comprises an RRC connection rejection message and second timer information; wherein the second timer information is the same as the first timer information, or the second timer information is generated based on the first timer information. And after waiting for the time indicated by the second timer information, the UE can resend the RRC connection establishment request to access the network so as to guarantee that the communication is normally carried out.

In one possible design, after receiving the second message sent by the central unit, the distributed unit sends an RRC connection reject message to the UE, where the RRC connection reject message includes second timer information, and the second timer information is used to indicate a time when the UE resends the RRC connection establishment request. Therefore, the UE can resend the RRC connection establishment request to access the network after receiving the RRC connection rejection message so as to guarantee the normal operation of communication.

In another possible design, the connection establishment request message may be an RRC connection establishment request, an RRC reestablishment request message, or an RRC recovery request message.

In a fifth aspect, an embodiment of the present application provides a radio resource control RRC connection establishment method, including: user unit UE sends RRC connection establishment request to distributed unit of access network; and the UE receives an RRC connection establishment message sent by the distributed unit, wherein the RRC connection establishment message comprises configuration information of a signaling radio bearer allocated by a central unit of the access network for the UE, and the configuration information is used for indicating the UE to configure the signaling radio bearer. Therefore, the UE can access the network after completing the configuration of the SRB1 according to the configuration information so as to guarantee the normal operation of communication.

In one possible design, the configuration information does not include configuration information of the signaling radio bearer allocated by the DU for the UE.

In another possible design, after receiving the RRC connection setup message, the UE configures the SRB1 of the UE according to configuration information of a higher layer protocol stack, such as configuration information of a PDCP protocol stack, of the SRB1 allocated to the UE by the CU in the RRC connection setup message. And under the condition that the RRC connection establishment message does not contain the configuration information of the bottom protocol stack of the signaling radio bearer, the UE uses the default configuration information of the bottom protocol stack of the signaling radio bearer. So that the UE can access the network after completing the SRB1 configuration according to the configuration information.

In another possible design, the UE receives an RRC connection setup message sent by the distributed unit, and sends an RRC connection setup complete message to the DU after the configuration is completed. Thereby informing the DU that the RRC connection setup is complete.

In a sixth aspect, an embodiment of the present application provides a method for establishing a radio resource control RRC connection, including: UE sends a connection establishment request message to a distributed unit of an access network; and then receiving an RRC connection rejection message sent by the distributed unit, wherein the RRC connection rejection message comprises second timer information, and the second timer information is used for indicating the time when the UE retransmits the RRC connection establishment request. Therefore, the UE can resend the RRC connection establishment request to access the network after waiting for the time indicated by the second timer information, in order to guarantee that the communication is performed normally.

In one possible design, the UE resends the RRC connection setup request to the distributed unit after the time indicated by the second timer information. The UE can be accessed to the network again so as to guarantee the normal operation of communication.

In another possible design, after the user unit UE sends the connection setup request message to the distributed unit of the access network, the DU allocates the first timer information to the UE if the DU rejects the connection setup request message of the UE. The second timer information is the same as the first timer information, or the second timer information is generated based on the first timer information, and the first timer information is used for indicating the time when the user unit UE generated by the distributed unit retransmits the RRC connection establishment request.

In a seventh aspect, an embodiment of the present application provides a central unit of an access network, where the central unit is configured to implement the methods and functions performed by the central unit in the first and second aspects, and is implemented by hardware/software, where the hardware/software includes modules corresponding to the functions.

In an eighth aspect, the present embodiment provides a distributed unit of an access network, where the distributed unit is configured to implement the methods and functions performed by the distributed unit in the third aspect and the fourth aspect, and the distributed unit is implemented by hardware/software, where the hardware/software includes modules corresponding to the functions.

In a ninth aspect, the present embodiments provide a subscriber unit configured to implement the methods and functions performed by the subscriber unit in the above fifth and sixth aspects, and implemented by hardware/software, where the hardware/software includes modules corresponding to the above functions.

In a tenth aspect, an embodiment of the present application provides another central unit, including: a processor and a memory, the processor executing a program stored in the memory for implementing the steps in the radio resource control RRC connection establishment method provided by the first aspect and the second aspect.

In one possible design, the central unit provided in the embodiment of the present application further includes a communication bus, where the communication bus is used to implement connection communication between the processor and the memory.

In another possible design, the central unit provided in the embodiments of the present application may include a module corresponding to the behavior of the central unit in the design for performing the method described above. The modules may be software and/or hardware.

In an eleventh aspect, an embodiment of the present application provides another distributed unit, including: a processor and a memory, the processor executing a program stored in the memory for implementing the steps in the radio resource control, RRC, connection establishment method provided in the third and fourth aspects.

In one possible design, the distributed unit provided in the embodiment of the present application further includes a communication bus, and the communication bus is used for implementing connection communication between the processor and the memory.

In another possible design, the distributed unit provided by the embodiment of the present application may include a module corresponding to the behavior of the distributed unit in the design for executing the method described above. The modules may be software and/or hardware.

In a twelfth aspect, an embodiment of the present application provides another subscriber unit, including: and the processor executes the program stored in the memory to implement the steps in the radio resource control RRC connection establishment method provided in the third aspect.

In one possible design, the subscriber unit provided in this embodiment of the present application further includes a communication bus, where the communication bus is used to implement connection communication between the processor and the memory.

In another possible design, the subscriber unit provided in the embodiment of the present application may include a module corresponding to the behavior of the subscriber unit in the design for executing the method described above. The modules may be software and/or hardware.

In a thirteenth aspect, the present application provides a computer-readable storage medium having stored therein instructions, which when executed on a computer, cause the computer to perform the method of the above-described aspects.

In a fourteenth aspect, the present application provides a computer program product containing instructions which, when run on a computer, cause the computer to perform the method of the above aspects.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the background art of the present application, the drawings required to be used in the embodiments or the background art of the present application will be described below.

Fig. 1 is a schematic architecture diagram of an access network system according to an embodiment of the present application;

fig. 2 is a flowchart illustrating an initial RRC connection establishment method according to an embodiment of the present application;

fig. 3 is a flowchart illustrating another RRC connection initial establishment method according to an embodiment of the present application;

fig. 4 is a flowchart illustrating an RRC establishment method according to an embodiment of the present application;

fig. 5 is a flowchart illustrating another RRC establishment method according to an embodiment of the present application;

fig. 6 is a flowchart illustrating another RRC establishment method according to an embodiment of the present application;

fig. 7 is a schematic structural diagram of a central unit of an access network according to an embodiment of the present application;

fig. 8 is a schematic structural diagram of a distributed unit of an access network according to an embodiment of the present application;

fig. 9 is a schematic structural diagram of a subscriber unit according to an embodiment of the present application;

fig. 10 is a schematic structural diagram of another central unit proposed in the embodiment of the present application;

FIG. 11 is a schematic structural diagram of another distributed unit proposed in the embodiments of the present application;

fig. 12 is a schematic structural diagram of another subscriber unit according to an embodiment of the present application.

Detailed Description

The embodiments of the present application will be described below with reference to the drawings.

Fig. 1 is a schematic diagram of an architecture of a network system according to an embodiment of the present disclosure, where the network system includes a User Equipment (UE) and an access network. The access network may include a base station, among other things. For example, a 5G base station (gNB), an access point, a node B or evolved node B (eNB), and so on. The gbb may be split into two parts according to protocol stack functionality: CU and DU. The CU and the DU are both logical nodes, and the CU may include Protocol stack entities such as a Service Data Protocol (SDAP), a Packet Data Convergence Protocol (PDCP), and a Radio Resource Control (RRC), and the DU includes Protocol stack entities such as a Medium Access Control (MAC), a physical layer (PHY), and a Radio Link Control (RLC). It is understood that the functional division between the CU and the DU may be in other forms, for example, the CU may include protocol stack entities such as service data protocol (SDAP), Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), and Radio Resource Control (RRC), and the DU may include protocol stack entities such as Media Access Control (MAC) and physical layer (PHY).

A gNB may comprise one CU and a plurality of DUs, which are connected via an interface, referred to as F1 interface in this application, and one CU may connect a plurality of DUs. A subscriber unit may refer to a device that provides voice and/or data connectivity to a user, may be connected to a computing device such as a laptop or desktop computer, or may be a stand-alone device such as a Personal Digital Assistant (PDA). A subscriber unit can also be a Station (STA), a system, a subscriber station, a mobile station, a remote station, an access point, a remote terminal, an access terminal, a user agent, or a user device. An access network refers to a device in an access network that communicates over the air-interface, through one or more sectors, with wireless terminals.

Referring to fig. 2, fig. 2 is a flowchart illustrating an initial RRC connection establishment method according to an embodiment of the present disclosure. As shown, at least the following steps are included:

s201, the UE sends an RRC connection establishment request (RRC connection request) to the DU.

S202, after receiving the RRC connection establishment request, the DU performs access control, and if the DU allows the UE to access the network, generates configuration information of a protocol stack of a radio access bearer (SRB) 1 for the UE, for example, configuration information of a bottom protocol stack. The configuration Information of the underlying protocol stack includes configuration Information of at least one of the protocol stacks of the RLC, MAC, or PHY, and the configuration Information is placed in a cell of the F1 interface, referred to as a DU to CU RRC Information cell in this application, and finally an initial uplink RRC transmission message (initial UL RRC transmission message) is sent to the CU, where the initial uplink RRC transmission message includes DU to CU RRC Information.

S203, after receiving the initial uplink RRC message, if the initial uplink RRC transmission message includes DU to CU RRC information, it is determined that the DU allows the UE to access the network, and if the CU also allows the UE to access the network, an RRC connection setup message is generated, which includes configuration information of a protocol stack of the SRB1 allocated by the CU for the UE, for example, configuration information of a higher layer protocol stack. The configuration information of the higher layer protocol stack may include PDCP configuration information. The RRC connection setup message may further include configuration information of a protocol stack of the SRB1 allocated to the UE by the DU in the DU toCU RRC information. Finally, the CU sends a downlink RRC transfer message (DL RRC message) to the DU, the downlink RRC transfer message including an RRC connection setup message.

S204, after receiving the downlink RRC transmission message sent by the CU, the DU sends an RRC connection setup message to the UE.

S205, after the UE receives the RRC connection establishment message, the SRB1 of the UE is configured according to the configuration information of the SRB1 high-level protocol stack distributed to the UE by the CU and the configuration information of the SRB1 bottom-level protocol stack distributed to the UE by the DU in the RRC connection establishment message. After the SRB1 is configured, the UE sends an RRC connection setup complete message to the DU.

S206, the DU sends an uplink RRC message (UL RRC message transfer message) to the CU, where the uplink RRC message includes an RRC connection setup complete message.

In the above-mentioned RRC connection initial establishment procedure, the DU allows the UE RRC connection establishment request in the access control. As shown in fig. 3, if the DU rejects the RRC connection setup request of the UE, the following steps are performed:

s301, the UE sends an RRC connection establishment request to the DU, where the RRC connection establishment request includes information of a cause value of an RRC connection establishment request initiated by the UE, such as emergency (emergency), high priority access (high priority access), or access network notification area update (RAN AU).

S302, after the DU receives the RRC connection establishment request sent by the UE, the DU rejects the RRC connection establishment request of the UE, and does not generate configuration information of a protocol stack of a radio access bearer (SRB) 1, for example, configuration information of a bottom protocol stack, for the UE. The configuration information of the underlying protocol stack includes configuration information of at least one of protocol stacks of RLC, MAC, or PHY. The reason why the DU rejects the UE may include: congestion of the DU, limited DU resources, shutdown of DU cells, failure of DU channel conditions not allowing serving UE or air interface link, etc.

S303, the DU sends an initial uplink RRC message (initial UL RRC message) to the CU.

S304, after the CU receives the initial uplink RRC message sent by the DU, the CU confirms that the DU rejects the UE to access, and the method for the CU to confirm that the DU rejects the UE to access the network comprises the following steps: and confirming that the second message does not comprise DU to CU RRC information, so that the CU generates an RRC connection rejection message for the UE.

S305, the CU sends an RRC connection reject message to the DU.

S306, after the DU receives the RRC connection reject message, the DU directly forwards the RRC connection reject message to the UE without parsing the RRC connection reject message. Therefore, in a high priority event request scenario, such as an emergency call, the UE cannot establish an RRC connection.

In a high priority event request scenario (e.g., an emergency call), the network side should ensure that the UE can access the network and obtain network services as much as possible. However, since the DU may be congested, the DU may deny the UE access to the network after receiving the RRC connection setup request sent by the UE. Under the condition of an emergency call, after the UE sends the RRC connection establishment request to the DU, since the DU cannot resolve the RRC connection establishment request, it cannot know that the UE is in the emergency call, which results in that the UE initiating the emergency call cannot access the network, seriously affects the network service quality, and cannot ensure the normal communication. The embodiment of the application provides the following solution to guarantee the normal operation of communication.

Referring to fig. 4, fig. 4 is a flowchart illustrating an RRC establishment method according to an embodiment of the present application, where the method includes, but is not limited to, the following steps:

s401, the UE sends an RRC connection establishment request (RRC connection request) to the DU. The RRC connection establishment request may include first cause value information (cause value) of the RRC connection establishment request initiated by the UE, where the first cause value information may be emergency (emergency), high priority access (high priority access), or access network notification area update (RANAU), and the like. Since the DU has no RRC protocol stack, the DU cannot parse the RRC connection setup request message, and thus cannot know the first cause value information.

S402, after the DU receives the RRC connection establishment request sent by the UE, if the DU does not allow the UE to access the network, that is, the DU cannot provide services for the UE, the DU will not generate configuration information of a protocol stack of the SRB1 for the UE, for example, configuration information of a bottom layer protocol stack. The configuration information of the underlying protocol stack includes configuration information of at least one of protocol stacks of RLC, MAC, or PHY.

S403, the DU sends a first message to the CU, where the first message includes an RRC connection setup request sent by the UE to the DU. The first message may not include the DU to CU RRC information. The first message may be an initial UL RRC message (initial UL RRC message transfer message). Optionally, the first message may further carry indication information, where the indication information is used to indicate that the DU rejects receiving the RRC connection establishment request.

S404, after the CU receives the first message sent by the DU, the CU confirms that the DU rejects the UE access, and the method for the CU to confirm that the DU rejects the UE to access the network comprises the following steps: it is confirmed that the second message does not include the DU to CU RRC information.

The CU is provided with an RRC protocol stack, can acquire first reason value information by analyzing the RRC connection establishment request information in the first message, and determines to allow the UE to establish the RRC connection according to the first reason value information. For example, if the first cause value information is urgent, the CU decides to provide a service to the terminal. That is, even if the DU denies the UE to access the network, the CU may decide again to let the UE access the network without fully accepting the access control decision of the DU, so the CU generates an RRC connection setup message for the UE including configuration information of the protocol stack of the SRB1 allocated by the CU for the UE, for example, configuration information of a higher layer protocol stack. The configuration information of the higher layer protocol stack may include PDCP configuration information.

S405, the CU sends a second message to the DU. The second message may include an RRC connection setup message, which is used to instruct the UE to establish an RRC connection. The second message may further include the first indication information. The first indication information is used to indicate that the DU allows the UE to establish RRC connection. Specifically, the following cases may be included but not limited: the first indication information may indicate that the DU establishes an RRC connection for the UE; or indicating the DU to provide service for the UE; or indicating the DU to allow UE access; or indicating the DU to allow the UE to establish RRC connection; or suggesting that the DU allows the UE to establish RRC connection; or suggesting the DU to provide service for the UE; or instruct the CU to allow UE access; or instruct the CU to decide to provide service to the UE, etc. The second message may be a downlink RRC transmission message (DL RRCmessage).

The first indication information may be first cause value information, second cause value information or indication value information. The second cause value information may be generated from or related to the first cause value information in the first message. For example, the first cause value is emergency and the second cause value is generated as an emergency call based on the first cause value, or the first cause value is emergency or high priority access and the second cause value is generated as a high priority event based on the first cause value. In addition, the indication value information may be a specific value, for example, 0 or 1. For example, when the indication value information is 1, the DU is indicated to establish RRC connection for the UE; or indicating the DU to provide service for the UE; or indicating the DU to allow UE access; or indicating the DU to allow the UE to establish RRC connection; or suggesting that the DU allows the UE to establish RRC connection; or suggesting the DU to provide service for the UE; or instruct the CU to allow UE access; or instruct the CU to decide to provide service to the UE, etc. The DU may reject the RRC connection setup request of the UE when the indicator value information is 0 or there is no indicator value information. The indicator value information may also indicate that the RRC connection setup message included in the second message needs to be sent on SRB 1. The DU confirms that the CU allows the UE to access the network by indicating that the RRC connection establishment contained in the second message needs to be sent on SRB1, in combination with the DU denying the UE to access the network in step S402.

S406, after the DU receives the second message, if it is determined that the UE is allowed to establish the RRC connection, the DU may send an RRC connection establishment message to the UE. The RRC connection setup message may include configuration information of the protocol stack of SRB1 allocated by the CU for the UE. Since the DU rejects the UE to access the network in step S402, there is no configuration information of the protocol stack of the SRB1 allocated to the UE, and therefore, the configuration information of the SRB1 protocol stack allocated to the UE by the DU may not be included.

Optionally, after the DU receives the second message sent by the CU, the DU may still refuse to establish the RRC access network of the UE, for example, in case of congestion and all service traffic is emergency calls. In this case, the DU may send a third message to the CU, where the third message includes second indication information indicating that the DU rejects the UE to establish the RRC connection. Optionally, the third message may further carry a reason why the DU rejects the UE to establish the RRC connection. It is to be understood that the DU may also be instructed by the message type information of the third message to reject the UE to establish the RRC connection.

S407, after the UE receives the RRC connection setup message, the UE configures the SRB1 of the UE according to the configuration information of the SRB1 higher layer protocol stack allocated to the UE by the CU in the RRC connection setup message, for example, the configuration information of the PDCP. In the case that there is no configuration information of the SRB1 underlying protocol stack in the RRC connection setup message, the UE may adopt default configuration information of the underlying protocol stack of SRB 1. After the configuration is completed, an RRC connection setup complete message is sent to the DU.

S408, the DU sends an uplink RRC message (UL RRC message transfer message) to the CU, where the uplink RRC message includes an RRC connection setup complete message.

In this embodiment, the DU first rejects the RRC connection establishment request of the UE, and the CU may determine to allow the UE to establish the RRC connection according to the cause value information, and send the indication information to the DU. The indication information may indicate that the DU establishes an RRC connection for the UE, or indicates that the DU provides a service for the UE, or indicates that the DU allows the UE to access, or indicates that the DU allows the UE to establish an RRC connection, or suggests that the DU provides a service for the UE; or instruct the CU to allow the UE access, or instruct the CU to decide to provide service for the UE, etc. And finally, the DU receives the UE to establish RRC connection according to the indication information, so that the UE can be rapidly accessed to the network in a high-priority event request scene, and the normal operation of communication is guaranteed.

As shown in fig. 5, fig. 5 is a flowchart illustrating another RRC establishment method according to an embodiment of the present application. The method comprises the following steps:

s501, the UE sends a first request message to the DU. The first request message may be an RRC connection establishment request (RRCconnection request), an RRC reestablishment request message, or an RRC recovery request message. The first request message includes first cause value information. The first cause value information is a cause of the UE initiating the first request message. The first cause value information may be an emergency, a high priority access or an access network notification area update, or the like. Since the DU has no RRC protocol stack, the DU cannot parse the first request message, and thus cannot know the first cause value information.

S502, after the DU receives the first request message sent by the UE, in some cases, for example, when the DU is congested, the DU does not allow the UE to access the network, and rejects the first request message of the UE, that is, the DU cannot provide service for the UE. The DU will not generate configuration information of the protocol stack of SRB1, e.g., configuration information of the underlying protocol stack, for the UE. The configuration information of the underlying protocol stack includes configuration information of at least one of protocol stacks of RLC, MAC, or PHY.

S503, the DU sends a second message to the CU, where the second message includes the first request message sent by the UE to the DU. The second message does not include the DU to CU RRC information. The second message may be an initial UL RRC message transfer message (initial UL RRC message).

S504, after the CU receives the second message sent by the DU, the CU confirms that the DU refuses the UE to access the network. The method for the CU to confirm that the DU rejects the UE to access the network comprises the following steps: it is confirmed that the second message does not include the DU to CU RRC information.

The CU is provided with an RRC protocol stack and can acquire the first reason value information by analyzing the first request message in the second message. Determining to allow the UE to establish the RRC connection with reference to the first cause value information. For example, if the first cause value information is urgent, the CU determines to provide a service to the terminal. That is, even if the DU denies the UE access to the network, the CU may decide to let the UE access to the network again without fully accepting the DU's access control decision.

S505, the CU sends a UE context setup request to the DU. The UE context setup request may include an RRC connection setup message for instructing the UE to establish an RRC connection. The UE context setup request may further include first indication information indicating that the DU allows the UE to establish the RRC connection. Specifically, the following cases may be included but not limited: the first indication information may indicate that the DU establishes an RRC connection for the UE; or indicating the DU to provide service for the UE; or indicating the DU to allow UE access; or indicating the DU to allow the UE to establish RRC connection; or suggesting that the DU allows the UE to establish RRC connection; or suggesting the DU to provide service for the UE; or instruct the CU to allow UE access; or instruct the CU to decide to provide service to the UE, etc.

The first indication information may be first cause value information, second cause value information or indication value information. The second cause value information may be generated from or related to the first cause value information in the first request message. For example, the first cause value is emergency and the second cause value is generated as an emergency call based on the first cause value, or the first cause value is emergency or high priority access and the second cause value is generated as a high priority event based on the first cause value. In addition, the indication value information may be a specific value, for example, 0 or 1. For example, when the indication value information is 1, the DU is indicated to establish RRC connection for the UE; or indicating the DU to provide service for the UE; or indicating the DU to allow UE access; or indicating the DU to allow the UE to establish RRC connection; or suggesting that the DU allows the UE to establish RRC connection; or suggesting the DU to provide service for the UE; or instruct the CU to allow UE access; or instruct the CU to decide to provide service to the UE, etc. The DU may reject the RRC connection setup request of the UE when the indicator value information is 0 or there is no indicator value information.

S506, after the DU receives the UE context setup request, if the DU determines that the UE is allowed to establish the RRC connection, the DU determines to provide a service for the UE or determines to allocate a corresponding resource to the UE. For example, configuration information of the underlying protocol stack of SRB1 is generated for the UE.

S507, the DU sends a UE context establishment response to the CU. The CU receives a UE context setup response from the DU.

It can be understood that after the DU receives the UE context setup request sent by the CU, the DU can still refuse to setup the RRC access network of the UE, for example, the DU is still congested and the service traffic is all emergency calls. The DU may send a UE context setup failure message to the CU. Optionally, the UE context setup failure message may further carry a reason why the DU rejects the UE to establish the RRC connection.

S508, the CU sends a third message to the DU. The third message includes a reply message to the first request message. In a scenario where the DU determines to provide a service for the UE, the reply message of the first request message may be an RRC connection setup message, an RRC connection reestablishment message, or an RRC recovery message. Optionally, the reply message of the first request message may include configuration information of the SRB1 higher-layer protocol stack allocated by the CU for the UE. In a scenario where the DU determines to reject to provide service to the UE, the reply message of the first request message may be an RRC connection reject message.

S509, the DU sends a reply message of the first request message to the UE.

In this embodiment of the present application, a DU first rejects a first request message of a UE, a CU may determine to allow the UE to establish an RRC connection according to cause value information, and send indication information to the DU through a UE context establishment request, where the indication information may indicate the DU to establish the RRC connection for the UE, or indicate the DU to provide a service for the UE, or indicate the DU to allow the UE to access, or indicate the DU to allow the UE to establish the RRC connection, or suggest the DU to allow the UE to establish the RRC connection; or propose DU to serve UE, or instruct CU to allow UE access, or instruct CU to decide to serve UE, etc. And finally, the DU receives the UE to establish RRC connection according to the indication information, so that the UE can be rapidly accessed to the network in a high-priority event request scene, and the normal operation of communication is guaranteed.

Referring to fig. 6, fig. 6 is a flowchart illustrating another RRC establishment method according to an embodiment of the present application. As shown in the figures, the steps of the embodiment of the present application at least include:

s601, the UE sends a connection establishment request message to the DU. The connection establishment request message may be an RRC connection establishment request, an RRC reestablishment request message, or an RRC recovery request message.

S602, after receiving the connection establishment request message, the DU performs access control, and if the DU rejects the connection establishment request message of the UE, the DU may allocate first timer information (wait timer) to the UE.

S603, the DU sends a first message to the CU, where the first message may include that the UE sends a connection establishment request message to the DU, and may also include first timer information. The first message does not include the DU to CU RRC Information. The first message may be an initial UL RRC message (initial UL RRC message transfer message).

S604, after the CU receives the first message sent by the DU, the CU confirms that the DU refuses the UE to access the network. The CU confirms that the DU rejects the UE to access the network, and the method comprises the following steps: the acknowledgement is made by the first message. For example, the first message does not include the DU to CU RRCinformation, i.e., the CU may confirm that the DU rejects the UE from accessing the network. Or the first message includes the first timer information, i.e. the CU can confirm that the DU denies the UE to access the network.

And under the condition that the CU determines to reject the UE to establish the RRC connection, the CU generates an RRC connection rejection message, wherein the RRC connection rejection message comprises the second timer information. The second timer information is the same as the first timer information, or the second timer information is generated based on the first timer information, or the second timer information may be regenerated by the CU itself.

S605, under the condition that the CU determines to reject the UE to establish the RRC connection, the CU sends a second message to the DU, wherein the second message comprises second timer information.

S606, the DU sends an RRC connection reject message to the UE, where the RRC connection reject message includes the second timer information, the UE starts the second timer information after receiving the RRC connection reject message, and the UE resends the connection setup request message to the DU after the time indicated by the second timer information.

In the embodiment of the present application, after the UE sends the connection setup request message to the DU, the DU rejects the connection setup request message of the UE, but allocates one timer information. The CU also rejects the connection setup request message of the UE after receiving the first message sent by the DU, and may send a second message to the DU, the second message including an RRC connection reject message and timer information. The DU forwards the RRC connection reject message to the UE, and after receiving the RRC connection reject message, the UE may start the timer information, and after waiting for the time indicated by the timer information, re-send the connection setup request message to the DU. The UE can access the network, and normal communication is guaranteed.

The method of the embodiments of the present application is set forth above in detail and the apparatus of the embodiments of the present application is provided below.

Referring to fig. 7, fig. 7 is a schematic structural diagram of a central unit of an access network according to an embodiment of the present application, where the central unit may include a receiving module 701 and a sending module 702, where details of each module are described as follows.

A receiving module 701, configured to receive a first message sent by a distributed unit of the access network, where the first message includes first cause value information that a user equipment UE sends an RRC connection establishment request to the distributed unit;

a sending module 702, configured to send a second message to the distributed unit, where the second message includes an RRC connection establishment message and first indication information, and the first indication information is used to indicate that the distributed unit allows the UE to establish an RRC connection.

Wherein, the second message is a downlink RRC transmission message or a UE context establishment request message.

The first indication information is second cause value information or indication value information.

Wherein the second cause value information is related to the first cause value information or the second cause value information is the same as the first cause value information.

Optionally, the receiving unit 701 is further configured to receive a third message sent by the distributed unit, where the third message includes second indication information, and the second indication information is used to indicate a reason why the distributed unit rejects the UE to establish the RRC connection.

Wherein the first cause value information is an emergency call, a high priority access or an access network notification area update.

Optionally, the receiving module 701 is further configured to receive a first message sent by a distributed unit of the access network, where the first message includes first timer information, and the first timer information is used to indicate a time when the distributed unit generates a UE resending an RRC connection establishment request; a sending module 702, further configured to send a second message to the distributed unit, where the second message includes second timer information, and the second timer information is used to indicate a time when the UE retransmits the RRC connection establishment request; wherein the second timer information is the same as the first timer information, or the second timer information is generated based on the first timer information.

It should be noted that the implementation of each module may also correspond to the corresponding description of the method embodiments shown in fig. 4 to 6, and perform the method and the function performed by the central unit described in the above embodiments.

Referring to fig. 8, fig. 8 is a schematic structural diagram of a distributed unit of an access network according to an embodiment of the present application, where the distributed unit may include a sending module 801 and a receiving module 802, where details of each module are described as follows.

A sending module 801, configured to send a first message to a central unit of an access network when a distributed unit of the access network rejects an RRC connection establishment request of a user equipment UE, where the first message includes first cause value information of the RRC connection establishment request;

a receiving module 802, configured to receive the second message sent by the central unit, where the second message includes an RRC connection establishment message and first indication information, and the first indication information is used to indicate that the distributed unit allows the UE to establish an RRC connection.

Optionally, the sending module 801 is further configured to send a third message to the central unit, where the third message includes second indication information, and the second indication information is used to indicate a reason why the distributed unit rejects the UE to establish the RRC connection.

Optionally, the sending module 801 is further configured to send the RRC connection establishment message to the UE, where the RRC connection establishment message includes configuration information of a protocol stack of a signaling radio bearer allocated by the central unit to the UE.

Optionally, the sending module 801 is further configured to send a first message to a central unit of the access network, where the first message includes first timer information, and the first timer information is used to indicate a time when the distributed unit generates a UE to resend an RRC connection establishment request; a receiving module 802, further configured to receive the second message sent by the central unit, where the second message includes an RRC connection reject message and second timer information; wherein the second timer information is the same as the first timer information, or the second timer information is generated based on the first timer information.

The sending module 801 is further configured to send an RRC connection reject message to the UE, where the RRC connection reject message includes second timer information, and the second timer information is used to indicate a time when the UE retransmits the RRC connection establishment request.

It should be noted that the implementation of each module may also correspond to the corresponding description of the method embodiments shown in fig. 4 to fig. 6, and perform the method and the function performed by the distributed unit in the foregoing embodiments.

Referring to fig. 9, fig. 9 is a schematic structural diagram of a subscriber unit according to an embodiment of the present application, where the subscriber unit may include a receiving module 901, a sending module 902, and a processing module 903, where details of each module are described below.

A sending module 901, configured to send an RRC connection establishment request to a distributed unit in an access network;

a receiving module 902, configured to receive an RRC connection setup message sent by a distributed unit of the access network, where the RRC connection setup message includes configuration information of a signaling radio bearer allocated by a central unit of the access network for the UE, and the configuration information is used to instruct the UE to configure the signaling radio bearer.

Optionally, the processing module 903 is configured to use default configuration information of a bottom protocol stack of a signaling radio bearer when the RRC connection setup message does not include configuration information of the bottom protocol stack of the signaling radio bearer.

Optionally, the sending module 901 is further configured to send a connection establishment request message to a distributed unit of an access network; the receiving module 902 is further configured to receive an RRC connection reject message sent by the distributed unit, where the RRC connection reject message includes second timer information, and the second timer information is used to indicate a time when the UE retransmits the RRC connection establishment request.

A sending module 901, configured to resend the RRC connection establishment request to the distributed unit after the time indicated by the second timer information.

It should be noted that the implementation of each module may also correspond to the corresponding description of the method embodiments shown in fig. 4 to fig. 6, and perform the method and the function performed by the subscriber unit in the above embodiments.

Referring to fig. 10, fig. 10 is a schematic structural diagram of another central unit according to the present application. As shown, the central unit may include: at least one processor 1001, at least one communication interface 1002, at least one memory 1003 and at least one communication bus 1004.

The processor 1001 may be a central processing unit, a general-purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. Which may implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. The processor may also be a combination of computing functions, e.g., comprising one or more microprocessors, a digital signal processor and a microprocessor, or the like. The communication bus 1004 may be a peripheral component interconnect standard PCI bus or an extended industry standard architecture EISA bus or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 10, but this is not intended to represent only one bus or type of bus. A communication bus 1004 is used to enable connective communication between these components. The communication interface 1002 of the device in this embodiment of the present application is used for performing signaling or data communication with other node devices. The memory 1003 may include a volatile memory, such as a nonvolatile dynamic random access memory (NVRAM), a phase change random access memory (PRAM), a Magnetoresistive Random Access Memory (MRAM), and the like, and may further include a nonvolatile memory, such as at least one magnetic disk memory device, an electrically erasable programmable read-only memory (EEPROM), a flash memory device, such as a NOR flash memory (NOR flash memory) or a NAND flash memory (EEPROM), and a semiconductor device, such as a Solid State Disk (SSD). The memory 1003 may optionally be at least one storage device located remotely from the processor 1001. A set of program codes is stored in the memory 1003, and the processor 1001 executes the programs executed by the above-described center unit in the memory 1003.

Receiving a first message sent by a distributed unit of the access network through a communication interface 1002, where the first message includes first cause value information for a user equipment UE to send an RRC connection establishment request to the distributed unit;

the communication interface 1002 sends a second message to the distributed unit, where the second message includes an RRC connection setup message and first indication information, and the first indication information is used to indicate that the distributed unit allows the UE to establish an RRC connection.

Optionally, the processor 1001 is further configured to perform the following operations:

and determining to allow the UE to establish RRC connection according to the first reason value information.

the communication interface 1002 receives a third message sent by the distributed unit, where the third message includes second indication information, and the second indication information is used to indicate a reason why the distributed unit rejects the UE to establish the RRC connection.

receiving a first message sent by a distributed unit of the access network through a communication interface 1002, where the first message includes first timer information, and the first timer information is used to indicate a time when the distributed unit generates a user element UE to resend an RRC connection establishment request;

sending a second message to the distributed unit through a communication interface 1002, the second message including second timer information, the second timer information being used for indicating a time when the UE retransmits the RRC connection establishment request;

wherein the second timer information is the same as the first timer information, or the second timer information is generated based on the first timer information.

Further, the processor may cooperate with the memory and the communication interface to perform the operations of the central unit in the embodiments of the above application.

With continuing reference to fig. 11, fig. 11 is a schematic diagram of another distributed unit structure proposed in the present application. As shown, the distributed unit may include: at least one processor 1101, at least one communication interface 1102, at least one memory 1103, and at least one communication bus 1104.

The processor 1101 may be any of the various types of processors mentioned above. The communication bus 1104 may be a peripheral component interconnect standard PCI bus or an extended industry standard architecture EISA bus or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 11, but this is not intended to represent only one bus or type of bus. A communication bus 1104 is used to enable connective communication between these components. The communication interface 1102 of the device in the embodiment of the present application is used for performing signaling or data communication with other node devices. The memory 1103 may be of the various types mentioned previously. The memory 1103 may optionally be at least one storage device located remotely from the processor 1101. A set of program codes is stored in the memory 1103 and the processor 1101 executes the programs executed by the above-described distributed units in the memory 1103.

In a case where a distributed unit of an access network rejects an RRC connection establishment request of a user element, UE, a communication interface 1102 sends a first message to a central unit of the access network, where the first message includes first cause value information of the RRC connection establishment request;

receiving, by a communication interface 1102, the second message sent by the central unit, where the second message includes an RRC connection establishment message and first indication information, and the first indication information is used to indicate that the distributed unit allows the UE to establish an RRC connection.

Optionally, the processor 1101 is further configured to perform the following operations:

and sending the RRC connection establishment message to the UE through a communication interface 1102, where the RRC connection establishment message includes configuration information of a protocol stack of a signaling radio bearer allocated by the central unit to the UE.

and sending a third message to the central unit through a communication interface 1102, where the third message includes second indication information, and the second indication information is used to indicate a reason why the distributed unit rejects the UE to establish the RRC connection.

sending a first message to a central unit of the access network via a communication interface 1102, the first message including first timer information, the first timer information being used to indicate a time when the distributed unit generates a user element, UE, to resend an RRC connection establishment request;

receiving the second message sent by the central unit through a communication interface 1102, wherein the second message comprises an RRC connection reject message and second timer information;

an RRC connection reject message is sent to the UE through the communication interface 1102, the RRC connection reject message including second timer information, the second timer information being used to indicate a time when the UE retransmits the RRC connection setup request.

Further, the processor may cooperate with the memory and the communication interface to perform operations of the distributed units in the embodiments of the above application.

With continued reference to fig. 12, fig. 12 is a schematic structural diagram of another subscriber unit proposed in the present application. As shown, the subscriber unit may include: at least one processor 1201, at least one communication interface 1202, at least one memory 1203 and at least one communication bus 1204.

The processor 1201 may be, among other things, a variety of types of processors as previously mentioned. The communication bus 1204 may be a peripheral component interconnect standard PCI bus or an extended industry standard architecture EISA bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 12, but this is not intended to represent only one bus or type of bus. A communication bus 1204 is used to enable connective communication between these components. The communication interface 1202 of the device in this embodiment of the present application is used for performing signaling or data communication with other node devices. The memory 1203 may be various types of memories as mentioned earlier. The memory 1203 may optionally also be at least one storage device located remotely from the aforementioned processor 1201. A set of program codes is stored in the memory 1203, and the processor 1201 executes the programs executed by the user units described above in the memory 1203.

Sending an RRC connection establishment request to a distributed unit of the access network over the communication interface 1202;

receiving, by a communication interface 1202, an RRC connection setup message sent by a distributed unit of the access network, where the RRC connection setup message includes configuration information of a signaling radio bearer allocated by a central unit of the access network for the UE, and the configuration information is used to instruct the UE to configure the signaling radio bearer.

Optionally, the processor 1201 is further configured to perform the following operations:

and using the default configuration information of the bottom protocol stack of the signaling radio bearer under the condition that the RRC connection establishment message does not contain the configuration information of the bottom protocol stack of the signaling radio bearer.

sending a connection establishment request message to a distributed element of the access network via the communication interface 1202;

an RRC connection reject message sent by the distributed unit is received through the communication interface 1202, where the RRC connection reject message includes second timer information indicating a time when the UE retransmits the RRC connection setup request.

the RRC connection establishment request is re-sent to the distributed unit after the time indicated by the second timer information through the communication interface 1202.

Further, the processor may cooperate with the memory and the communication interface to perform the operations of the subscriber unit in the embodiments of the above application.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the application to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

The above-mentioned embodiments further explain the objects, technical solutions and advantages of the present application in detail. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A Radio Resource Control (RRC) connection establishment method, comprising:

a central unit of an access network receives a first message sent by a distributed unit of the access network, wherein the first message comprises first reason value information of an RRC connection establishment request sent by a user unit UE to the distributed unit;

the central unit sends a second message to the distributed unit, wherein the second message comprises an RRC connection establishment message and first indication information, and the first indication information is used for indicating the distributed unit to allow the UE to establish the RRC connection.

2. The method of claim 1, wherein the second message is a downlink RRC transmission message or a UE context setup request message.

3. The method of claim 1 or 2, wherein the first indication information is second cause value information or indication value information.

4. The method of claim 3, wherein the second cause value information is related to the first cause value information or the second cause value information is the same as the first cause value information.

5. The method of any of claims 1-4, wherein the central unit sends a second message to the distributed units comprising:

and the central unit sends a second message to the distributed unit under the condition that the central unit determines that the distributed unit rejects the access of the UE.

6. The method of any of claims 1-5, wherein after the central unit sends the second message to the distributed units, further comprising:

and the central unit receives a third message sent by the distributed unit, wherein the third message comprises second indication information, and the second indication information is used for indicating the reason why the distributed unit rejects the UE to establish the RRC connection.

7. The method of any of claims 1-6, wherein the first cause value information is an emergency call, a high priority access, or an access network notification area update.

8. A Radio Resource Control (RRC) connection establishment method, comprising:

under the condition that a distributed unit of an access network rejects an RRC connection establishment request of a user Unit (UE), the distributed unit sends a first message to a central unit of the access network, wherein the first message comprises first reason value information of the RRC connection establishment request;

and the distributed unit receives the second message sent by the central unit, wherein the second message comprises an RRC connection establishment message and first indication information, and the first indication information is used for indicating that the distributed unit allows the UE to establish the RRC connection.

9. The method of claim 8, wherein the second message is a downlink RRC transmission message or a UE context setup request message.

10. The method of claim 8 or 9, wherein the first indication information is second cause value information or indication value information.

11. The method of claim 10, wherein the second cause value information is related to the first cause value information or the second cause value information is the same as the first cause value information.

12. The method of any of claims 8-11, wherein after the distributed unit receives the second message sent by the central unit, further comprising:

and the distributed unit sends the RRC connection establishment message to the UE, wherein the RRC connection establishment message comprises configuration information of a protocol stack of a signaling radio bearer distributed to the UE by the central unit.

13. The method of any of claims 8-12, wherein after the distributed unit receives the second message sent by the central unit, further comprising:

and the distributed unit sends a third message to the central unit, wherein the third message comprises second indication information, and the second indication information is used for indicating the reason why the distributed unit rejects the UE to establish the RRC connection.

14. The method of any of claims 8-13, wherein the first cause value information is an emergency call, a high priority access, or an access network notification area update.

15. A Radio Resource Control (RRC) connection establishment method, comprising:

user unit UE sends RRC connection establishment request to distributed unit of access network;

and the UE receives an RRC connection establishment message sent by the distributed unit, wherein the RRC connection establishment message comprises configuration information of a signaling radio bearer allocated to the UE by a central unit of the access network, and the configuration information is used for indicating the UE to configure the signaling radio bearer.

16. The method of claim 15, wherein after the UE receives the RRC connection setup message sent by the distributed unit, further comprising:

and under the condition that the RRC connection establishment message does not contain configuration information of a bottom protocol stack of the signaling radio bearer, the UE uses the default configuration information of the bottom protocol stack of the signaling radio bearer.

17. A central unit of an access network, comprising:

a receiving module, configured to receive a first message sent by a distributed unit of the access network, where the first message includes first cause value information that a user equipment UE sends an RRC connection establishment request to the distributed unit;

a sending module, configured to send a second message to the distributed unit, where the second message includes an RRC connection establishment message and first indication information, and the first indication information is used to indicate that the distributed unit allows the UE to establish an RRC connection.

18. The central unit according to claim 17, wherein the second message is a downlink RRC transfer message or a UE context setup request message.

19. The central unit according to claim 17 or 18, characterized in that the first indication information is second cause value information or indication value information.

20. The hub unit of claim 19, wherein the second cause value information is related to the first cause value information or the second cause value information is the same as the first cause value information.

21. The central unit according to any of claims 17-20,

the receiving unit is further configured to receive a third message sent by the distributed unit, where the third message includes second indication information, and the second indication information is used to indicate a reason why the distributed unit rejects the UE to establish the RRC connection.

22. The central unit according to any of claims 17-21, wherein the first cause value information is an emergency call, a high priority access, or an access network notification area update.

23. A distributed unit of an access network, comprising:

a sending module, configured to send a first message to a central unit of an access network when a distributed unit of the access network rejects an RRC connection establishment request of a user equipment UE, where the first message includes first cause value information of the RRC connection establishment request;

a receiving module, configured to receive the second message sent by the central unit, where the second message includes an RRC connection establishment message and first indication information, and the first indication information is used to indicate that the distributed unit allows the UE to establish an RRC connection.

24. The distributed unit of claim 23, wherein the second message is a downlink RRC transmission message or a UE context setup request message.

25. The distributed unit of claim 23 or 24, wherein the first indication information is second cause value information or indication value information.

26. The distributed unit of claim 25, wherein the second cause value information is related to the first cause value information or the second cause value information is the same as the first cause value information.

27. The distributed unit of any of claims 23-26,

the sending module is further configured to send a second message to the distributed unit when the central unit determines that the distributed unit rejects the UE access.

28. The distributed unit of any of claims 23-27,

the sending module is further configured to send the RRC connection establishment message to the UE, where the RRC connection establishment message includes configuration information of a protocol stack of a signaling radio bearer allocated by the central unit to the UE.

29. The distributed unit of any of claims 23-28,

the sending module is further configured to send a third message to the central unit, where the third message includes second indication information, and the second indication information is used to indicate a reason why the distributed unit rejects the UE to establish the RRC connection.

30. The distributed element of any of claims 23-29, wherein the first cause value information is an emergency call, a high priority access, or an access network notification area update.

31. A user element, UE, comprising:

a sending module, configured to send an RRC connection establishment request to a distributed unit of an access network;

a receiving module, configured to receive an RRC connection setup message sent by the distributed unit, where the RRC connection setup message includes configuration information of a signaling radio bearer allocated by a central unit of the access network for the UE, and the configuration information is used to instruct the UE to configure the signaling radio bearer.

32. The UE of claim 31, wherein the UE further comprises:

a processing module, configured to use default configuration information of the bottom protocol stack of the signaling radio bearer when the RRC connection setup message does not include the configuration information of the bottom protocol stack of the signaling radio bearer.