A communication method and device

Abstract

The embodiment of the present application provides a communication method and apparatus, which relates to the field of communication and can avoid the loss of downlink data when a terminal device communicates with a network side. The method is as follows: the DU receives the first control plane information from the CU‑CP, and the first control plane information is used to indicate the restoration of the RRC connection of the terminal device; if the DU is the last DU connected before the terminal device enters the inactive state, the DU sends a first indication message to the CU‑UPF, and the first indication message enables the data packet corresponding to the terminal device to be sent to the DU; if the DU is not the last DU connected before the terminal device enters the inactive state, the DU sends a second indication message to the CU‑UPF, and the second indication message enables the establishment of a downlink connection between the CU‑UPF and the DU, and the data packet of the terminal device is sent to the DU. The embodiment of the present application is applied to a 5G communication system.

Description

Technical Field

[0001] The present application relates to the field of communications, and in particular to a communication method and device. Background Art

[0002] In the fifth generation (5 th In the 5G generation (5G) mobile communication system, by splitting the radio access network (RAN) into a centralized processing node (centralized unit, CU) and a distributed processing node (distributed unit, DU), the base station network can be adjusted more flexibly. Among them, CU can also be called gNB-CU, and DU can also be called gNB-DU. Furthermore, according to different functions, the CU can be divided into the control plane (CU control plane, CU-CP) of the centralized processing node and the user plane (CU user plane, CU-UP) of the centralized processing node. Among them, CU-CP can also be called gNB-CU-CP, and CU-UP can also be called gNB-CU-UP.

[0003] With the maturity of CU / DU separation technology, the widespread deployment of multi-access edge computing (MEC) and user plane function (UPF) network elements (the UPF network element (UPF) is deployed in the same physical room as the gNB-CU), the joint deployment of gNB-CU, UPF and MEC may become the mainstream. In this scenario, since the gNB-CU is deployed in the same physical room as the UPF, the UPF and gNB-CU-UP may eventually be combined into one network element in order to reduce the number of data plane transmission hops, save costs, and terminate the data plane security node in the core network.

[0004] In the scenario where UPF and gNB-CU-UP are co-installed, there is currently no corresponding solution for how terminal devices communicate with the network side. Summary of the invention

[0005] The embodiments of the present application provide a communication method and apparatus, which are applied to the scenario where UPF and CU-UP are co-installed, and can avoid the loss of downlink data when the terminal device communicates with the network side.

[0006] In the first aspect, an embodiment of the present application provides a communication method, which is applied to a DU in a centralized unit CU-distributed unit DU architecture, and the method includes: the DU receives a first control plane information from a centralized unit-control plane CU-CP, and the first control plane information is used to indicate the restoration of the radio resource control RRC connection of the terminal device; if the DU is the last DU connected before the terminal device enters an inactive state, the DU sends a first indication information to a centralized unit-user plane function network element (centralized unit-user plane function, CU-UPF), and the first indication information enables the data packet corresponding to the terminal device to be sent to the DU; if the DU is not the last DU connected before the terminal device enters an inactive state, the DU sends a second indication information to the CU-UPF, and the second indication information enables the establishment of a downlink connection between the CU-UPF and the DU, and the data packet of the terminal device is sent to the DU. It should be noted that the DU can send the first indication information to the CU-UPF, or the DU can send the second indication information to the CU-UPF, that is, the first indication information or the second indication information is sent selectively.

[0007] Based on the method provided in the embodiment of the present application, if the DU is the last DU connected before the terminal device enters the inactive state, the DU sends a first indication message to the CU-UPF to enable the CU-UPF to send the data packet corresponding to the terminal device to the DU; if the DU is not the last DU connected before the terminal device enters the inactive state, the DU sends a second indication message to the CU-UPF to enable the CU-UPF to establish a downlink connection with the DU and send the data packet of the terminal device to the DU. After the DU obtains the data packet corresponding to the terminal device from the CU-UPF, it can send the data packet to the terminal device through the air interface resources to prevent the terminal device from losing its downlink data in the inactive state.

[0008] In a possible implementation, before the distributed unit DU receives the first control plane information from the centralized unit-control plane CU-CP, the method further includes: the DU receives an RRC recovery request from the terminal device; the DU sends an initial uplink radio resource control (RRC) message to the CU-CP, and the initial uplink RRC message is used to request the restoration of the RRC connection of the terminal device. That is, after the DU receives the RRC recovery request from the terminal device, it sends an initial uplink RRC message to the CU-CP. The DU can be the last DU connected before the terminal device enters the inactive state (i.e., no DU switching occurs), or it can be another DU (i.e., DU switching occurs).

[0009] In a possible implementation, before the distributed unit DU receives the first control plane information from the centralized unit-control plane CU-CP, the method also includes: the DU receives a first downlink data packet of the terminal device from the CU-UPF, the header of the first downlink data packet includes a first quality of service flow identity (QoS (quality of service) flow identity, QFI) information, and the first QFI information is used to identify the quality of service (quality of service, QoS) flow of the first downlink data packet; when the terminal device is in an inactive state, the DU sends user plane information to the CU-UPF, the user plane information is used to instruct the CU-UPF to stop sending the second downlink data packet corresponding to the terminal device, the header of the second downlink data packet includes the first QFI information, and the user plane information is also used to instruct the CU-UPF to cache the first downlink data packet and the second downlink data packet.

[0010] Based on the method provided in the embodiment of the present application, after the DU receives the downlink data packet from the CU-UPF, it can notify the CU-UPF through the user plane information to stop sending and caching the corresponding downlink data packet. Since the DU does not have the function of caching data, by instructing the CU-UPF to stop sending and caching the corresponding downlink data packet, data packet loss can be avoided, and the CU-UPF can be prevented from sending useless data to the DU to occupy communication resources.

[0011] In a possible implementation, the method also includes: the DU sends second control plane information to the CU-CP, the second control plane information includes first QFI information and first paging policy indicator (PPI) information, and the first QFI information and the first PPI information are used to determine the paging policy of the terminal device.

[0012] In a possible implementation, the method further includes: the DU receives a third downlink data packet corresponding to the terminal device from the CU-UPF, the header of the third downlink data packet includes second QFI information and second PPI information, and the second QFI information is different from the first QFI information; the DU sends third control plane information to the CU-CP, the third control plane information includes second QFI information and second PPI information, and the second QFI information and second PPI information are used to determine the paging strategy of the terminal device. The CU-CP can determine the paging strategy again according to the second PPI information in the third control plane information. If the priority of the Paging strategy determined according to the first PPI information is lower than the priority of the Paging strategy determined according to the second PPI information, the CU-CP can update the Paging strategy of the terminal device; if the priority of the Paging strategy determined according to the first PPI information is not lower than (higher than or equal to) the priority of the Paging strategy determined according to the second PPI information, the CU-CP can still paging the terminal device according to the Paging strategy determined by the first PPI information.

[0013] In a possible implementation, the method also includes: the DU receives fourth control plane information from the CU-CP, the fourth control plane information is used to instruct the DU to release the air interface resources of the terminal device, and retain the connection between the DU and the centralized unit-user plane function network element CU-UPF and the context of the terminal device; the DU releases the air interface resources of the terminal device.

[0014] Based on the method provided in the embodiment of the present application, when CU-CP triggers the UE to enter an inactive state, CU-CP can instruct DU to release relevant air interface resources and retain the user plane connection and related UE context with the jointly set up network element CU-UPF. CU-UPF is not aware of the above process and can be distinguished from the process of initiating paging by UPF (equivalent to CU-UPF) detecting downlink data under RRC Idle, thereby solving the problem that the existing technology cannot support RRC Inactive technology.

[0015] In one possible implementation, before the DU receives the fourth control plane information from the CU-CP, the method also includes: the DU receives the fifth control plane information from the CU-CP, and the fifth control plane information is used to indicate the conditions for the terminal device to enter the inactive state; the DU sends the sixth control plane information to the CU-CP, and the sixth control plane information is used to indicate whether the terminal device meets the conditions for entering the inactive state.

[0016] In the second aspect, an embodiment of the present application provides a communication method, which is applied to a centralized unit-control plane CU-CP in a centralized unit CU-distributed unit DU architecture, the method comprising: the CU-CP sends first control plane information to the distributed unit DU, the first control plane information being used to restore the wireless resource control RRC connection of the terminal device; if the DU is the last DU connected before the terminal device enters an inactive state, the first control plane information includes an uplink port identifier of the centralized unit-user plane function network element CU-UPF; if the DU is not the last DU connected before the terminal device enters an inactive state, the first control plane information includes an uplink port identifier of the CU-UPF, and downlink port information of the last DU serving the terminal device.

[0017] Based on the method provided in the embodiment of the present application, the CU-CP can send the first control plane information to the DU to restore the RRC connection of the terminal device. In addition, if DU switching does not occur, the DU can obtain the data packet corresponding to the terminal device from the CU-UPF according to the uplink port identifier of the CU-UPF. If DU switching occurs, the DU can obtain the data packet corresponding to the terminal device from the CU-UPF according to the uplink port identifier of the CU-UPF and the downlink port information of the last DU serving the terminal device (the data packet sent by the core network when the terminal device is in an inactive period). Then, the DU can send the data packet to the terminal device through the air interface resources to prevent the terminal device from losing its downlink data in the inactive state.

[0018] In one possible implementation, if the DU is not the last DU connected before the terminal device enters an inactive state, the method further includes: the CU-CP sends a terminal device context release message to the last DU connected before the terminal device enters an inactive state, and the terminal device context release message is used to instruct the last DU connected before the terminal device enters an inactive state to release the connection with the centralized unit-user plane function network element CU-UPF and the context of the terminal device.

[0019] In a possible implementation, the method further includes: the CU-CP receives second control plane information from the DU, the second control plane information includes first QFI information and first PPI information, and the first QFI information and the first PPI information are used by the CU-CP to determine a paging strategy for the terminal device.

[0020] In a possible implementation, the method also includes: the CU-CP receives third control plane information from the DU, the third control plane information includes second QFI information and second PPI information, the second QFI information and the second PPI information are used by the CU-CP to determine a paging strategy for the terminal device, the second QFI information is different from the first QFI information, and the second PPI information is different from the first PPI information.

[0021] In a possible implementation, the method also includes: the CU-CP sends fourth control plane information to the DU, the fourth control plane information is used to instruct the DU to release the air interface resources of the terminal device and retain the connection between the DU and the user plane network element of the core network and the context of the terminal device.

[0022] In one possible implementation, before the CU-CP sends the fourth control plane information to the DU, the method also includes: the CU-CP sends the fifth control plane information to the DU, and the fifth control plane information is used to indicate the conditions for the terminal device to enter the inactive state; the CU-CP receives the sixth control plane information from the DU, and the sixth control plane information is used to indicate whether the terminal device meets the conditions for entering the inactive state.

[0023] In a third aspect, an embodiment of the present application provides a communication method, including: a centralized unit-user plane function network element CU-UPF receives a first indication message from a distributed unit DU, the DU is the last DU connected before the terminal device enters an inactive state, and the first indication information enables a data packet corresponding to the terminal device to be sent to the DU; or, the CU-UPF receives a second indication message from the DU, the DU is not the last DU connected before the terminal device enters an inactive state, the second indication information enables the establishment of a downlink connection between the CU-UPF and the DU, and the data packet of the terminal device is sent to the DU.

[0024] Based on the method provided in the embodiment of the present application, if the DU is the last DU connected before the terminal device enters the inactive state, the CU-UPF receives first indication information from the DU, and the first indication information enables the CU-UPF to send the data packet corresponding to the terminal device to the DU; if the DU is not the last DU connected before the terminal device enters the inactive state, the CU-UPF receives second indication information from the DU, and the second indication information enables the CU-UPF to establish a downlink connection with the DU and send the data packet of the terminal device to the DU. After the DU obtains the data packet corresponding to the terminal device from the CU-UPF, it can send the data packet to the terminal device through the air interface resources to prevent the terminal device from losing its downlink data in the inactive state.

[0025] In a possible implementation, the method also includes: CU-UPF sends a first downlink data packet to DU, and the header of the first downlink data packet carries first service quality flow identifier QFI information; CU-UPF receives user plane information from DU, and the user plane information is used to instruct CU-UPF to stop sending a second downlink data packet corresponding to the terminal device, and the header of the second downlink data packet includes the first QFI information. The user plane information is also used to instruct CU-UPF to cache the first downlink data packet and the second downlink data packet; CU-UPF stops sending the second downlink data packet corresponding to the terminal device and caches the first downlink data packet and the second downlink data packet.

[0026] In a fourth aspect, an embodiment of the present application provides a communication device, which is a DU in a centralized unit CU-distributed unit DU architecture, including: a receiving unit for receiving first control plane information from a centralized unit-control plane CU-CP, the first control plane information being used to indicate restoration of a wireless resource control RRC connection of a terminal device; a sending unit for sending first indication information to a centralized unit-user plane function network element CU-UPF, the first indication information enabling a data packet corresponding to the terminal device to be sent to the DU; or, a sending unit for sending second indication information to the CU-UPF, the second indication information enabling establishment of a downlink connection between the CU-UPF and the DU, and a data packet of the terminal device being sent to the DU.

[0027] In a possible implementation, the receiving unit is further used to: receive an RRC recovery request from the terminal device; the sending unit is further used to send an initial uplink RRC message to the CU-CP, and the initial uplink RRC message is used to request to restore the RRC connection of the terminal device.

[0028] In a possible implementation, the receiving unit is also used to: receive a first downlink data packet of a terminal device from the CU-UPF, the packet header of the first downlink data packet includes first quality of service flow identification QFI information, and the first QFI information is used to identify the quality of service QoS flow of the first downlink data packet; when the terminal device is in an inactive state, the sending unit is also used to send user plane information to the CU-UPF, and the user plane information is used to instruct the CU-UPF to stop sending the second downlink data packet corresponding to the terminal device, the packet header of the second downlink data packet includes the first QFI information, and the user plane information is also used to instruct the CU-UPF to cache the first downlink data packet and the second downlink data packet.

[0029] In a possible implementation, the sending unit is further used to: send second control plane information to the CU-CP, the second control plane information includes first QFI information and first paging policy identifier PPI information, the first QFI information and the first PPI information are used to determine the paging policy of the terminal device.

[0030] In a possible implementation, the receiving unit is also used to: receive a third downlink data packet corresponding to the terminal device from the CU-UPF, the header of the third downlink data packet includes second QFI information and second PPI information, and the second QFI information is different from the first QFI information; the sending unit is also used to send third control plane information to the CU-CP, the third control plane information includes second QFI information and second PPI information, and the second QFI information and second PPI information are used to determine the paging strategy of the terminal device.

[0031] In one possible implementation, the receiving unit is also used to: receive fourth control plane information from the centralized unit-control plane CU-CP, the fourth control plane information is used to instruct the DU to release the air interface resources of the terminal device, and retain the connection between the DU and the centralized unit-user plane function network element CU-UPF and the context of the terminal device through the storage unit; a processing unit is used to release the air interface resources of the terminal device.

[0032] In a possible implementation, the receiving unit is also used to: receive fifth control plane information from the CU-CP, the fifth control plane information is used to indicate the conditions for the terminal device to enter an inactive state; the sending unit is also used to send sixth control plane information to the CU-CP, the sixth control plane information is used to indicate whether the terminal device meets the conditions for entering an inactive state.

[0033] In the fifth aspect, an embodiment of the present application provides a communication device, which is a centralized unit-control plane CU-CP in a centralized unit CU-distributed unit DU architecture, including: a sending unit, used to send first control plane information to the distributed unit DU, the first control plane information is used to restore the wireless resource control RRC connection of the terminal device; if the DU is the last DU connected before the terminal device enters an inactive state, the first control plane information includes an uplink port identifier of the centralized unit-user plane function network element CU-UPF; if the DU is not the last DU connected before the terminal device enters an inactive state, the first control plane information includes the uplink port identifier of the CU-UPF, and the downlink port information of the last DU serving the terminal device.

[0034] In one possible implementation, if the DU is not the last DU connected before the terminal device enters the inactive state, the sending unit is also used to: send a terminal device context release message to the last DU connected before the terminal device enters the inactive state, and the terminal device context release message is used to instruct the last DU connected before the terminal device enters the inactive state to release the connection with the centralized unit-user plane function network element CU-UPF and the context of the terminal device.

[0035] In a possible implementation, it also includes a receiving unit, which is used to: receive second control plane information from the DU, the second control plane information includes first QFI information and first PPI information, and the first QFI information and the first PPI information are used by the CU-CP to determine a paging strategy for the terminal device.

[0036] In one possible implementation, the receiving unit is also used to: receive third control plane information from the DU, the third control plane information including second QFI information and second PPI information, the second QFI information and the second PPI information are used by the CU-CP to determine a paging strategy for the terminal device, the second QFI information is different from the first QFI information, and the second PPI information is different from the first PPI information.

[0037] In a possible implementation, the sending unit is also used for: the CU-CP sends fourth control plane information to the DU, and the fourth control plane information is used to instruct the DU to release the air interface resources of the terminal device and retain the connection between the DU and the user plane network element of the core network and the context of the terminal device.

[0038] In one possible implementation, the sending unit is also used to: send fifth control plane information to the DU, the fifth control plane information is used to indicate the conditions for the terminal device to enter an inactive state; the receiving unit is also used to receive sixth control plane information from the DU, the sixth control plane information is used to indicate whether the terminal device meets the conditions for entering an inactive state.

[0039] In the sixth aspect, an embodiment of the present application provides a communication device, which is a centralized unit-user plane function network element CU-UPF, including: a receiving unit, used to receive a first indication message from a distributed unit DU, the DU is the last DU connected before the terminal device enters an inactive state, and the first indication information enables a data packet corresponding to the terminal device to be sent to the DU; or, a receiving unit, used to receive a second indication message from the DU, the DU is not the last DU connected before the terminal device enters an inactive state, and the second indication information enables the establishment of a downlink connection between the CU-UPF and the DU, and the data packet of the terminal device is sent to the DU.

[0040] In a possible implementation, it also includes a sending unit, which is used to: send a first downlink data packet to the DU, the packet header of the first downlink data packet carries the first service quality flow identifier QFI information; the receiving unit is used to receive user plane information from the DU, the user plane information is used to instruct the CU-UPF to stop sending the second downlink data packet corresponding to the terminal device, the packet header of the second downlink data packet includes the first QFI information, and the user plane information is also used to instruct the CU-UPF to cache the first downlink data packet and the second downlink data packet; the sending unit is used to stop sending the second downlink data packet corresponding to the terminal device and cache the first downlink data packet and the second downlink data packet through the cache unit.

[0041] In the seventh aspect, a communication device is provided, which may be a DU, comprising: a processor and a memory; the memory is used to store computer-executable instructions, and the processor executes the computer-executable instructions stored in the memory so that the device executes a method as described in any one of the above-mentioned first aspects.

[0042] In an eighth aspect, a communication device is provided, which may be a CU-CP, comprising: a processor and a memory; the memory is used to store computer-executable instructions, and the processor executes the computer-executable instructions stored in the memory so that the device performs a method as described in any one of the second aspects above.

[0043] In the ninth aspect, a communication device is provided, which may be a CU-UPF, comprising: a processor and a memory; the memory is used to store computer execution instructions, and the processor executes the computer execution instructions stored in the memory so that the device performs a method as described in any one of the third aspects above.

[0044] In a tenth aspect, a computer-readable storage medium is provided, wherein instructions are stored in the computer-readable storage medium, and when the computer-readable storage medium is run on a computer, the computer can execute any one of the methods in the first to third aspects above.

[0045] In an eleventh aspect, a computer program product comprising instructions is provided, which, when executed on a computer, enables the computer to execute any one of the methods of the first to third aspects above.

[0046] In a twelfth aspect, a circuit system is provided, the circuit system comprising a processing circuit, and the processing circuit is configured to execute a method as described in any one of the first to third aspects above.

[0047] In a thirteenth aspect, a chip is provided, comprising a processor, wherein the processor is coupled to a memory, wherein the memory stores program instructions, and when the program instructions stored in the memory are executed by the processor, the method of any one of the first to third aspects is implemented.

[0048] In a fourteenth aspect, a communication system is provided, comprising a communication device according to any one of the fourth aspect, a communication device according to any one of the fifth aspect, and a communication device according to any one of the sixth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic diagram of a network architecture in a CU / DU separation scenario provided in an embodiment of the present application;

[0050] Figure 2A A schematic diagram of a protocol stack of a gNB-DU and a gNB-CU-CP provided in an embodiment of the present application;

[0051] Figure 2B A schematic diagram of a protocol stack of a gNB-DU and a gNB-CU-UP provided in an embodiment of the present application;

[0052] Figure 3A distribution diagram of a gNB-DU, gNB-CU-CP and gNB-CU-UP provided in an embodiment of the present application;

[0053] Figure 4 A schematic diagram of a network architecture in a scenario where a UPF and gNB-CU-UP are co-located provided in an embodiment of the present application;

[0054] Figure 5 A schematic diagram of a network architecture in a scenario where a UPF and a gNB-CU-UP are co-located in another embodiment of the present application;

[0055] Fig. 6A A schematic diagram of a control plane protocol stack architecture in a scenario where a gNB-CU-CP and a UPF are co-located is provided in an embodiment of the present application;

[0056] Figure 6B A schematic diagram of a user plane protocol stack architecture for a scenario where gNB-CU-CP and UPF are co-located provided in an embodiment of the present application;

[0057] Figure 7 A schematic diagram of the structure of a DU, CU-CP or CU-UPF provided in an embodiment of the present application;

[0058] Figure 8 A signal interaction diagram provided in an embodiment of the present application;

[0059] Fig. 9 A schematic diagram of the structure of another DU provided in an embodiment of the present application;

[0060] Fig.10 A schematic diagram of the structure of another CU-CP provided in an embodiment of the present application;

[0061] Fig.11 A schematic diagram of the structure of another CU-UPF provided in an embodiment of the present application. DETAILED DESCRIPTION

[0062] In order to make the description of the following embodiments clear and concise, a brief introduction to the relevant concepts or technologies is first given:

[0063] CU / DU separation technology is an important feature of 5G. This technology can adjust the base station network more flexibly. In addition, this technology has good benefits for load balancing and maximizing resource utilization. It has better support for solving tidal effects, deploying dual connections, edge computing, business diversion, and intelligent operation and maintenance.

[0064] like Figure 1As shown, a schematic diagram of the network architecture in a CU / DU separation scenario is shown. In the CU / DU separation scenario, the gNB can be divided into gNB-CU-CP, gNB-CU-UP and gNB-DU. The gNB-CU-CP can communicate with the gNB-CU-UP through the E1 interface, the gNB-CU-CP can communicate with the gNB-DU through the F1-C interface, and the gNB-CU-UP can communicate with the gNB-DU through the F1-U interface. The terminal device can access the network through the gNB-DU. The gNB-CU-CP can communicate with the access and mobility management function (AMF) network element through the next generation network (NG) 2 interface (N2 for short), the AMF can communicate with the session management function (SMF) network element through the N11 interface (N11 for short), the SMF can communicate with the UPF network element through the N4 interface (N4 for short), the UPF network element accesses the data network (DN) through the N6 interface (N6 for short), and the UPF network element can communicate with the gNB-CU-UP through the N3 interface (N3 for short).

[0065] Among them, AMF is responsible for access and mobility management functions. It can receive non-access stratum (NAS) signaling (including session management (SM) signaling) of terminal devices and related signaling of access network devices, complete the user registration process and forwarding of SM signaling and mobility management. SMF is responsible for session management functions and completes the establishment, release, update and other processes related to protocol data unit (PDU) sessions.

[0066] Among them, the terminal device can also be called a terminal, and the terminal can be a wireless terminal or a wired terminal. The wireless terminal can be a device that provides voice and / or data connectivity to a user, a handheld device with a wireless connection function, or other processing devices connected to a wireless modem. The wireless terminal can communicate with one or more core networks via a radio access network (RAN). The wireless terminal can be a mobile terminal, such as a mobile phone (or a "cellular" phone) and a computer with a mobile terminal. For example, the wireless terminal can be a portable, pocket-sized, handheld, computer-built-in or vehicle-mounted mobile device, or a personal communication service (PCS) phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station or a personal digital assistant (PDA) and other devices. A wireless terminal may also be referred to as a system, a subscriber unit, a subscriber station, a mobile station, a mobile station, a remote station, a remote terminal, an access terminal, a user agent, a user device or user equipment. A wireless terminal may also be a desktop computer, a portable computer, a network server, a personal digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, a communication device, an embedded device, etc., without limitation herein.

[0067] like Figure 2A As shown in the figure, in the CU / DU separation architecture, the RRC and packet data convergence protocol (PDCP) protocol stacks can be distributed in the gNB-CU-CP (CU-CP), and the radio link control (RLC), media access control (MAC) and physical layer (PHY) protocol stacks can be distributed in the gNB-DU (DU). Figure 2BAs shown, the service data adaptation protocol (SDAP) and PDCP protocol stack can be distributed in gNB-CU-UP (CU-UP).

[0068] like Figure 3 As shown, gNB-DU can be deployed in a distributed manner, gNB-CU-CP and gNB-CU-UP can be deployed in a centralized manner, and one gNB-CU-CP can control multiple gNB-CU-UPs, which can be flexibly grouped and distributed in different areas to serve gNB-DUs in different areas. One gNB-CU-UP can be connected to multiple gNB-DUs, and one gNB-DU can be connected to one or more gNB-CU-UPs.

[0069] With the maturity of CU / DU separation technology and the widespread deployment of MEC and downlink UPF, UPF and gNB-CU-UP can be combined into one network element, denoted as CU-UPF. It should be noted that CU-UPF in the embodiment of the present application is only a naming method, and it does not exclude the possibility of defining other possible names in existing or future protocols to replace the above names. Figure 4 As shown, CU-UPF can be uniformly scheduled and managed by SMF. CU-UPF can communicate with gNB-DU through F1-U interface, CU-UPF can access DN through N6 interface, and gNB-CU-CP can cancel the management authority of gNB-CU-UP (i.e. CU-UPF) (cancel the original E1 interface), or only retain some authority and system structure that do not affect security.

[0070] In the scenario where UPF and gNB-CU-UP are co-located, there is currently no corresponding solution for how the terminal device communicates with the network side. For example, when the terminal device enters the RRC inactive state (RRC Inactive / RRC_INACTIVE), since the gNB-CU-UP and UPF are one network element (i.e., CU-UPF) after the co-location, if the gNB-CU-UP (equivalent to CU-UPF) detects downlink data and initiates paging, it is no different from the UPF (equivalent to CU-UPF) detecting downlink data and initiating paging in the RRC idle state (RRC Idle / RRC_IDLE), and the support for RRC Inactive technology is lost. Among them, RRC_INACTIVE can be considered as an intermediate state between RRC_IDLE and RRC connected state (RRC_CONNECTED). In summary, it can be considered that the air interface state of the UE in RRC_INACTIVE is similar to RRC_IDLE, and the connection to 5GC is similar to RRC_CONNECTED. In the embodiment of the present application, RRC Inactive / RRC_INACTIVE may be referred to as Inactive or inactive state.

[0071] An embodiment of the present application provides a communication method, which is applied to the scenario where CU-UP and UPF are jointly set up (UPF and CU-UP are jointly set up as CU-UPF). The gNB-CU-CP can instruct the gNB-DU to release relevant air interface resources and retain the user plane connection and related UE context with the jointly set up network element CU-UPF. The CU-UPF is not aware of the above process and can be distinguished from the process of initiating paging by UPF (equivalent to CU-UPF) detecting downlink data under RRC Idle, thereby solving the problem that the existing technology cannot support RRC Inactive technology.

[0072] Furthermore, after the gNB-DU detects the downlink data packet from the CU-UPF, it can notify the CU-UPF through the user plane information to stop sending the corresponding downlink data packet and cache the downlink data packet. Since the DU does not have the function of caching data, by instructing the CU-UPF to stop sending and caching the corresponding downlink data packet, data packet loss can be avoided, and the CU-UPF can be prevented from sending useless data to the DU to occupy communication resources.

[0073] If the DU is the last DU connected before the terminal device enters the inactive state, the DU may send a first indication message to the CU-UPF, and the first indication message enables the data packet corresponding to the terminal device to be sent to the DU; if the DU is not the last DU connected before the terminal device enters the inactive state, the DU may send a second indication message to the CU-UPF, and the second indication message enables the establishment of a downlink connection between the CU-UPF and the DU, and the data packet of the terminal device is sent to the DU. In this way, after the DU obtains the data packet corresponding to the terminal device from the CU-UPF, it can send the data packet to the terminal device through the air interface resources to prevent the terminal device from losing its downlink data in the inactive state. It should be noted that the DU may send the first indication message to the CU-UPF, or the DU may send the second indication message to the CU-UPF, that is, the first indication message or the second indication message is sent selectively.

[0074] The communication method and device provided in the embodiments of the present application can be applied to 5G mobile communication systems or new radio (NR), etc. The technical solution provided in the present application can also be applied to future communication systems, such as the sixth generation mobile communication system. Among them, the communication system can be a future evolved public land mobile network (PLMN) network, a device to device (D2D) network, a machine to machine (M2M) network, an Internet of Things (IoT) network or other network, which is not limited in the present application.

[0075] The network architecture applicable to the embodiments of the present application is as follows: Figure 5 As shown, one gNB-CU-CP can control multiple gNB-DUs. When the UE has no downlink service data, the UE can enter the inactive state, that is, release the air interface transmission resources, but retain the relevant resources of the NG-U. When downlink data from the core network arrives, the gNB-CU-CP instructs all gNB-DUs within its control range to initiate Paging. After receiving the Paging message initiated by the gNB-DU, the UE can restore the connection with the gNB-DU and the gNB-CU-UP. It should be noted that when the downlink data of the core network arrives, if the UE moves (moving) from the service range of a gNB-DU within the control range of the gNB-CU-CP to the service range of another gNB-DU, that is, DU switching occurs, and the UE can establish a connection with the new gNB-DU; if the downlink data of the core network arrives, the UE is still in the service range of the last gNB-DU it connected to before entering the inactive state, that is, no DU switching occurs, and the UE can restore the connection with the gNB-DU.

[0076] in addition, Figure 5 For the description of other network elements, please refer to Figure 1 and Figure 4 The relevant description is not repeated here. Of course, Figure 5 The network architecture involved may also include other network elements, such as unified data management (UDM) network elements, policy control function (PCF) network elements, authentication server function (AUSF) network elements, network exposure function (NEF) network elements / network function storage function (NRF) network elements / network slice selection function (NSSF), unified data repository (UDR) or network storage function (NRF) and other network elements or devices, without specific limitation.

[0077] It should be noted that Figure 5 The names of the network elements and the interfaces between the network elements are only examples. In a specific implementation, the names of the network elements and the interfaces between the network elements may be other names, and the embodiments of the present application do not specifically limit this.

[0078] like Fig. 6A The figure shows a schematic diagram of the control plane protocol stack architecture in the scenario where gNB-CU-CP and UPF are co-located. Among them, the equivalent protocol layers between UE and DU include RLC layer, MAC layer and PHY. The equivalent protocol layers between UE and CU-CP include RRC layer and PDCP layer. The equivalent protocol layers between UE and AMF include non-access stratum (NAS) layer. The equivalent protocol layers between AMF and SMF include NAS layer. Since the control of gNB-CU-CP over CU-UPF has been cancelled, PDCP and SDAPConfig messages related to security and quality of service (QoS) flow control can be finally sent to CU-UPF in the control plane through the path of CU-CP->AMF->SMF->CU-UPF.

[0079] like Figure 6BThe figure shows the user plane protocol stack architecture diagram for the scenario where gNB-CU-CP and UPF are co-located. The equivalent protocol layers between UE and CU-UPF include SDAP and PDCP layers, and the equivalent protocol layers between UE and UPF include protocol data unit (PDU) layer. CU-UPF directly communicates with DN ( Figure 6B The peer protocol layers between CU-UPF and UPF include the general packet radio service (GPRS) tunneling protocol user plane (GTP-U), the user datagram protocol (UDP) / internet protocol (IP) layer, the L2 layer and the L1 layer.

[0080] For the convenience of description, gNB-DU, gNB-CU-CP and gNB-CU-UP are referred to as DU, CU-CP and CU-UP respectively below. It should be noted that CU-CP (gNB-CU-CP), CU-UP (gNB-CU-UP) and DU (gNB-DU) in the embodiment of the present application are only a naming method, and other possible names defined in existing or future protocols to replace the above names are not excluded.

[0081] The DU, CU-CP or CU-UPF in the embodiment of the present application can be Figure 7 This is achieved by the communication equipment in. Figure 7 The hardware structure diagram of the communication device provided in the embodiment of the present application is shown as follows. The communication device 700 includes at least one processor 701 , a communication line 702 , a memory 703 and at least one communication interface 704 .

[0082] The processor 701 may be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of the program of the present application.

[0083] The communication link 702 may include a pathway to transmit information between the above-mentioned components.

[0084] The communication interface 704 uses any transceiver or other device for communicating with other devices or communication networks, such as Ethernet, radio access network (RAN), wireless local area networks (WLAN), etc.

[0085] The memory 703 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory may exist independently and be connected to the processor via a communication line 702. The memory may also be integrated with the processor.

[0086] The memory 703 is used to store computer-executable instructions for executing the solution of the present application, and the execution is controlled by the processor 701. The processor 701 is used to execute the computer-executable instructions stored in the memory 703, thereby realizing the communication method provided in the following embodiments of the present application.

[0087] Optionally, the computer-executable instructions in the embodiments of the present application may also be referred to as application code, which is not specifically limited in the embodiments of the present application.

[0088] In a specific implementation, as an embodiment, the processor 701 may include one or more CPUs, such as Figure 7 CPU0 and CPU1 in.

[0089] In a specific implementation, as an embodiment, the communication device 700 may include multiple processors, such as Figure 7 701 and processor 705 in the embodiment of the present invention. Each of these processors may be a single-CPU processor or a multi-CPU processor. The processor herein may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0090] The communication method provided by the embodiment of the present application will be described in detail below in conjunction with the accompanying drawings. It should be noted that the names of the various network elements, the names of the messages between the various network elements, or the names of the various parameters in the messages in the following embodiments of the present application are only examples, and other names may also be used in the specific implementation, and the embodiments of the present application do not specifically limit this.

[0091] In the description of the present application, unless otherwise specified, "at least one" means one or more, and "a plurality of" means two or more than two. In addition, in order to facilitate the clear description of the technical solutions of the embodiments of the present application, in the embodiments of the present application, the words "first", "second" and the like are used to distinguish the same items or similar items with substantially the same functions and effects. Those skilled in the art will understand that the words "first", "second" and the like do not limit the quantity and execution order, and the words "first", "second" and the like do not necessarily limit the difference.

[0092] In an embodiment of the present application, control plane information (for example, first control plane information to fifth control plane information) refers to information used for interaction between DU and CU-CP. The control plane information may also be called by other names, which is not limited in the present application.

[0093] For ease of understanding, the communication method provided in the embodiments of the present application is described in detail below with reference to the accompanying drawings.

[0094] like Figure 8 As shown, an embodiment of the present application provides a communication method, including:

[0095] 801. CU-CP sends control plane information (fourth control plane information) to DU.

[0096] The fourth control plane information is used to instruct the DU to release the air interface resources of the terminal device and retain the connection between the DU and the core network user plane network element and the context of the terminal device so that the terminal device can enter an inactive state. Exemplarily, the fourth control plane information can be a UE Context Release Command, which includes an RRC Release message.

[0097] Optionally, before the CU-CP sends the fourth control plane information to the DU, the CU-CP may send the fifth control plane information to the DU, where the fifth control plane information is used to indicate the conditions for the terminal device to enter the inactive state, so that the DU can determine whether the terminal device needs to enter the inactive state based on the fifth control plane information, and report the corresponding situation to the CU-CP. Exemplarily, the fifth control plane information may be a UE Context Setup Request, which includes an Inactivity Monitoring Request.

[0098] 802. DU receives fourth control plane information from CU-CP.

[0099] The DU can release the air interface resources of the terminal device according to the fourth control plane information. Exemplarily, after receiving the fourth control plane information, the DU can send an RRC Release message to the UE to release the relevant air interface resources. In addition, the DU retains the connection between the DU and the user plane network element of the core network and the context of the terminal device, that is, the connection between the DU and the user plane network element of the core network is not disconnected and the context of the terminal device is not deleted. Optionally, the DU can also feedback the execution status of the RRC Release to the CU-CP, for example, it can report whether the RRC Release is executed successfully through an indication (Indicator).

[0100] Optionally, before receiving the fourth control plane information from the CU-CP, the DU may receive the fifth control plane information from the CU-CP, where the fifth control plane information is used to indicate the conditions for the terminal device to enter the inactive state, that is, the CU-CP may inform the DU under what conditions (situations) the terminal device enters the inactive state, so that the DU detects the downlink data transmission status of the terminal device to determine whether the terminal device meets the conditions for entering the inactive state. Exemplarily, the CU-CP may send a UEContext Setup Request to the DU, and the UE Context Setup Request may be used to configure the UE context. The UE ContextSetup Request may carry an Inactivity Monitoring Request, which is used for the DU to trigger RRC Inactive, that is, for the DU to determine whether the terminal device has the conditions to enter the inactive state, or for the DU to determine whether the terminal device needs to enter the inactive state.

[0101] After receiving the fifth control plane information, DU may send feedback information of the fifth control plane information to CU-CP, and the feedback information is used to feedback to CU-CP whether it supports Inactivity Monitoring. If DU supports InactivityMonitoring, DU may send sixth control plane information to CU-CP, and the sixth control plane information is used to indicate whether the terminal device meets the conditions for entering the inactive state. Exemplarily, the sixth control plane information may include relevant information about the UE entering the inactive state (for example, the UE has no downlink data for a long time, at which time it can be considered that the UE has a need to enter the inactive state). Exemplarily, the sixth control plane information may be UE inactivity notification. CU-CP may determine whether the terminal device meets the conditions for entering the inactive state or does not meet the conditions for entering the inactive state based on the sixth control plane information. If the terminal device meets the conditions for entering the inactive state, CU-CP determines to make the UE enter the inactive state, which may be to change the UE's state from a connected state to an inactive state, that is, to execute step 801.

[0102] Based on the method provided in the embodiment of the present application, when CU-CP triggers the UE to enter an inactive state, CU-CP can instruct DU to release relevant air interface resources and retain the user plane connection and related UE context with the jointly set up network element CU-UPF. CU-UPF is not aware of the above process and can be distinguished from the process of initiating paging by UPF (equivalent to CU-UPF) detecting downlink data under RRC Idle, thereby solving the problem that the existing technology cannot support RRC Inactive technology.

[0103] The above steps 801-802 illustrate how to make the UE enter an inactive state in a CU-UPF co-location scenario. When the UE enters an inactive state, since the DU retains the connection with the CU-UPF, the DU may receive a data packet from the terminal device from the CU-UPF and needs to perform corresponding processing, that is, this embodiment may also include steps 803-811.

[0104] It should be noted that steps 801-802 and subsequent steps 803-811 may be independent of each other, that is, the terminal device may be put into an inactive state through steps 801-802 or through other methods, and this application does not limit this.

[0105] 803. CU-UPF sends the first downlink data packet of the terminal device to DU.

[0106] The header of the first downlink data packet carries the first QFI information. The first QFI can be used to identify the 5G QoS flow corresponding to the first downlink data packet. The 5G QoS flow is the finest granularity of QoS forwarding processing in the 5G system, and all traffic mapped to the same 5G QoS flow receives the same forwarding processing (for example, scheduling strategy, queue management strategy, rate shaping strategy, RLC configuration, etc.).

[0107] 804. DU receives the first downlink data packet of the terminal device from CU-UPF.

[0108] After the DU receives the first downlink data packet, if it is determined that the terminal device is in an inactive state, step 805 can be executed.

[0109] 805. When the terminal device is in an inactive state, the DU sends user plane information to the CU-UPF.

[0110] Among them, the user plane information is used to instruct the CU-UPF to stop sending the second downlink data packet corresponding to the terminal device. This is because the terminal device is in an inactive state, that is, the RRC connection between the DU and the terminal device has been disconnected, and the DU cannot send data packets to the terminal device. Therefore, the DU can instruct the CU-UPF to stop sending the second downlink data packet corresponding to the terminal device. The user plane information is also used to instruct the CU-UPF to cache the first downlink data packet and the second downlink data packet. This is because the DU does not have the function of caching data packets, so the CU-UPF can cache the first downlink data packet and the second downlink data packet.

[0111] The header of the second downlink data packet includes the first QFI information, that is, the second data packet and the first data packet both belong to the QoS flow (5G QoS flow) corresponding to the first QFI. The second data packet may include all or part of the data packets in the QoS flow corresponding to the first QFI except the first data packet.

[0112] The user plane information may be carried in a PDU, for example, in a downlink data delivery status (DDDS) PDU. Alternatively, the user plane information may be carried in a header of a data packet.

[0113] Among them, DDDS PDU is a control PDU sent by the user plane from DU to CU-UP through the F1-U interface. The function of this control PDU is to report the transmission status of PDCP PDU (including PDCP sequence number (SN) number and packet loss, etc.) for flow control. DDDS PDU can be used to indicate CU-UP on the user plane that this message (message carrying DDDS PDU) is the last DL Status Report, and no uplink or downlink data will be sent from this channel (communication channel for transmitting DDDS PDU) in the future. Alternatively, DDDS PDU can be used to indicate that this message is Initial DL DATA DELIVERY STATUS, so that CU-UP can start sending downlink data packets to DU. Exemplarily, the structure of DDDS PDU can be as shown in Table 1.

[0114] Table 1

[0115]

[0116] It should be noted that an extended bit may be added on the basis of the DDDS PDU shown in Table 1, and the above-mentioned user plane information may be carried in the extended bit, or the DDDS PDU may not be in the format shown in Table 1, and the DDDS PDU may be redesigned, which is not limited in this application.

[0117] 806. CU-UPF receives user plane information from DU.

[0118] CU-UPF may stop sending the second downlink data packet corresponding to the terminal device according to the user plane information, and cache the first downlink data packet and the second downlink data packet.

[0119] 807. DU sends the second control plane information to CU-CP.

[0120] Among them, the second control plane information includes the first QFI information and the first PPI information, and the first QFI information and the first PPI information are used to determine the paging strategy of the terminal device. Optionally, the second control plane information may also include gNB-CU-CP UEF1AP ID and gNB-DU UE F1AP ID for identifying the terminal device. Exemplarily, the second control plane information may be carried in DL Data Notification.

[0121] 808. CU-CP receives second control plane information from DU.

[0122] CU-CP queries the 5G QoS identifier (5G QoS Identifier, 5QI) and allocation and retention priority (ARP) according to the first QFI information. Among them, 5QI is used to determine the QoS parameters of the QoS flow, such as latency, packet error rate, etc., and ARP is used to determine the priority between different QoS Flows. CU-CP determines the Paging strategy based on the first PPI information. After determining the Paging strategy, it can start sending Paging messages to DUs within the control range of CU-CP. The DU that receives the Paging message can initiate Paging with the UE within its coverage.

[0123] It should be noted that there is no necessary execution order between step 807-step 808 and step 805-step 806. Step 805-step 806 may be executed first, and then step 807-step 808; step 807-step 808 may be executed first, and then step 805-step 806; or step 805-step 806 and step 807-step 808 may be executed at the same time, and this embodiment does not make any specific limitations on this.

[0124] After step 807-step 808, if the CU-UPF continues to send data packets corresponding to the second QFI to the DU, the embodiment of the present application may further include steps 809-step 811.

[0125] 809. DU receives the third downlink data packet corresponding to the terminal device from CU-UPF.

[0126] The header of the third downlink data packet includes second QFI information and second PPI information, the second QFI information is different from the first QFI information, and the second PPI information is the same as or different from the first PPI information.

[0127] 810. DU sends third control plane information to CU-CP.

[0128] The third control plane information includes the second QFI information and the second PPI information, and the second QFI information and the second PPI information are used to determine the paging strategy of the terminal device. Exemplarily, the third control plane information can be carried in a new DL Data Notification message, which is different from the DL Data Notification message carrying the second control plane information.

[0129] 811. CU-CP receives third control plane information from DU.

[0130] CU-CP can determine the Paging policy again based on the second PPI information in the third control plane information. If the priority of the Paging policy determined based on the first PPI information is lower than the priority of the Paging policy determined based on the second PPI information, CU-CP can update the Paging policy of the terminal device; if the priority of the Paging policy determined based on the first PPI information is not lower than (higher than or equal to) the priority of the Paging policy determined based on the second PPI information, CU-CP can still Paging the terminal device according to the Paging policy determined according to the first PPI information.

[0131] Based on the method provided in the embodiment of the present application, after the DU receives the downlink data packet from the CU-UPF, it can notify the CU-UPF through the user plane information to stop sending and caching the corresponding downlink data packet. Since the DU does not have the function of caching data, by instructing the CU-UPF to stop sending and caching the corresponding downlink data packet, data packet loss can be avoided, and the CU-UPF can be prevented from sending useless data to the DU to occupy communication resources.

[0132] Steps 803 to 811 describe how to trigger paging (i.e., paging the terminal device) in the CU-UPF co-location scenario. After triggering the paging, the DU can receive an RRC recovery request from the terminal device, and the DU can request the CU-CP to restore the RRC connection of the terminal device, that is, the embodiment of the present application can also include steps 812 to 818.

[0133] It should be noted that steps 803 to 811 and steps 812 to 818 may be independent of each other, that is, paging may be triggered by steps 803 to 811 or by other methods, which is not limited in this application.

[0134] 812. DU receives an RRC resume request (RRC Resume Request) from the terminal device.

[0135] The terminal device refers to the terminal device that receives the paging message.

[0136] 813. DU sends an initial uplink RRC message (Initial UL RRC Message Transfer) to CU-CP.

[0137] Among them, the initial uplink RRC message is used to request the restoration of the RRC connection of the terminal device.

[0138] 814. CU-CP sends first control plane information to DU, where the first control plane information is used to restore the RRC connection of the terminal device.

[0139] If the current DU (the DU that sends the initial uplink RRC message to the CU-CP) is the last DU connected before the terminal device enters the inactive state, the first control plane information may also carry the uplink port identifier of the CU-UPF, so that the DU can request the data of the terminal device from the CU-UPF according to the uplink port identifier of the CU-UPF. Among them, the uplink port identifier of the CU-UPF may be, for example, the F1-U UL tunnel endpoint identifier (tunnel endpoint identifier, TEID). If the current DU is not the last DU connected before the terminal device enters the inactive state, the first control plane information may carry not only the uplink port identifier of the CU-UPF, but also the downlink port information of the last DU (Last Serving DU) connected before the terminal device enters the inactive state. The DU may request the data of the terminal device from the CU-UPF according to the uplink port identifier of the CU-UPF, and the data of the terminal device may be the Last Serving DU indicating that the CU-UPF caches the data. Exemplarily, the first control plane information may be carried in the UEContext Setup Request.

[0140] At the same time, CU-CP can interact with the UE through RRC Resume signaling to convert the UE from an inactive state to a connected state.

[0141] In addition, if the DU is not the last DU connected before the terminal device enters the inactive state, the CU-CP can send a terminal device context release message to the last DU connected before the terminal device enters the inactive state. The terminal device context release message is used to instruct the last DU connected before the terminal device enters the inactive state to release the connection with the CU-UPF and the context of the terminal device. That is, if a DU switch occurs, the CU-CP can send a UE ContextRelease message to the Last Serving DU to instruct the DU to release the connection with the CU-UPF and the UE context, thereby saving communication resources.

[0142] 815. DU receives the first control plane information from CU-CP.

[0143] If the DU is the last DU connected before the terminal device enters the inactive state, the DU can execute step 816. If the DU is not the last DU connected before the terminal device enters the inactive state, the DU can execute step 818.

[0144] 816. If the DU is the last DU connected before the terminal device enters the inactive state, the DU sends a first indication message to the CU-UPF, and the first indication message enables the data packet corresponding to the terminal device to be sent to the DU.

[0145] That is, if DU switching does not occur, the DU sends a first indication message to the CU-UPF, and the first indication message enables the data packet corresponding to the terminal device to be sent to the DU. The data packet corresponding to the terminal device may include a first downlink data packet and a second downlink data packet. Exemplarily, the first indication message may be carried in a DDDS PDU.

[0146] 817. CU-UPF receives the first indication information from DU.

[0147] After receiving the first indication information from the DU, the CU-UPF may send the data packets (the first downlink data packet and the second downlink data packet) corresponding to the terminal device to the DU.

[0148] Optionally, CU-UPF can report the changes of the F1-U port of DU to AMF / SMF.

[0149] 818. If the DU is not the last DU connected before the terminal device enters the inactive state, the DU sends a second indication message to the CU-UPF, and the second indication message enables the establishment of a downlink connection between the CU-UPF and the DU, and the data packet of the terminal device is sent to the DU.

[0150] That is, if DU switching occurs, the DU sends a second indication message to the CU-UPF, which enables the CU-UPF to establish a downlink connection with the DU and send the data packet of the terminal device (buffered by the Last Serving DU indication) to the DU. The second indication message can be carried in the DDDS PDU.

[0151] 819. CU-UPF receives the second indication information from DU.

[0152] After receiving the second indication information from the DU, the CU-UPF establishes a downlink connection with the DU and sends the data packets (the first downlink data packet and the second downlink data packet) corresponding to the terminal device to the DU.

[0153] Optionally, CU-UPF can report the changes of the F1-U port of DU to AMF / SMF.

[0154] Based on the method provided in the embodiment of the present application, if the DU is the last DU connected before the terminal device enters the inactive state, the DU sends a first indication message to the CU-UPF to enable the CU-UPF to send the data packet corresponding to the terminal device to the DU; if the DU is not the last DU connected before the terminal device enters the inactive state, the DU sends a second indication message to the CU-UPF to enable the CU-UPF to establish a downlink connection with the DU and send the data packet of the terminal device to the DU. After the DU obtains the data packet corresponding to the terminal device from the CU-UPF, it can send the data packet to the terminal device through the air interface resources to prevent the terminal device from losing its downlink data in the inactive state.

[0155] In the embodiments provided in the present application above, the methods provided in the embodiments of the present application are introduced from the perspectives of DU, CU-CP, CU-UPF, and the interaction between DU, CU-CP and CU-UPF. In order to implement the functions of the methods provided in the embodiments of the present application above, DU, CU-CP and CU-UPF may include hardware structures and / or software modules to implement the above functions in the form of hardware structures, software modules, or hardware structures plus software modules. Whether one of the above functions is executed in the form of hardware structures, software modules, or hardware structures plus software modules depends on the specific application and design constraints of the technical solution.

[0156] In the case of dividing each functional module into corresponding functional modules, Fig. 9 A possible structural diagram of DU9 involved in the above embodiment is shown, and the DU9 includes: a receiving unit 901 and a sending unit 902. In the embodiment of the present application, the receiving unit 901 is used to receive first control plane information from a centralized unit-control plane CU-CP, and the first control plane information is used to indicate the restoration of the radio resource control RRC connection of the terminal device; the sending unit 902 is used to send first indication information to the centralized unit-user plane function network element CU-UPF, and the first indication information enables the data packet corresponding to the terminal device to be sent to the DU; or the sending unit 902 is used to send second indication information to the CU-UPF, and the second indication information enables the establishment of a downlink connection between the CU-UPF and the DU, and the data packet of the terminal device is sent to the DU.

[0157] exist Figure 8 In the method embodiment shown, the receiving unit 901 is used to support DU execution Figure 8 The sending unit 902 is used to support the DU to perform Figure 8 The processes 805, 807, 810, 813 and 816 in the above method embodiment. All relevant contents of each step involved in the above method embodiment can be referred to the functional description of the corresponding functional module, which will not be repeated here.

[0158] The receiving unit 901 or the sending unit 902 may be Figure 7 The communication interface 704 in.

[0159] In the case of dividing each functional module into corresponding functional modules, Fig.10 A possible structural diagram of the CU-CP10 involved in the above embodiment is shown, and the CU-CP10 includes: a sending unit 1001. In an embodiment of the present application, the sending unit 1001 is used to send the first control plane information to the distributed unit DU, and the first control plane information is used to restore the radio resource control RRC connection of the terminal device; if the DU is the last DU connected before the terminal device enters the inactive state, the first control plane information includes the uplink port identifier of the centralized unit-user plane function network element CU-UPF; if the DU is not the last DU connected before the terminal device enters the inactive state, the first control plane information includes the uplink port identifier of the CU-UPF, and the downlink port information of the last DU serving the terminal device.

[0160] exist Figure 8 In the method embodiment shown, the sending unit 1001 is used to support CU-CP execution Figure 8 Optionally, the CU-UPF may further include a receiving unit 1002 for supporting the CU-CP to perform Figure 8 The processes 808 and 811 in the above method embodiment. All relevant contents of each step involved in the above method embodiment can be referred to the functional description of the corresponding functional module, which will not be repeated here.

[0161] The sending unit 1001 or the receiving unit 1002 may be Figure 7 The communication interface 704 in.

[0162] In the case of dividing each functional module into corresponding functional modules, Fig.11 A possible structural diagram of the CU-UPF11 involved in the above-mentioned embodiment is shown, and the CU-UPF11 includes: a receiving unit 1101. In an embodiment of the present application, the receiving unit 1101 is used to receive a first indication information from a distributed unit DU, where the DU is the last DU connected before the terminal device enters an inactive state, and the first indication information enables a data packet corresponding to the terminal device to be sent to the DU; or the receiving unit 1101 is used to receive a second indication information from the DU, where the DU is not the last DU connected before the terminal device enters an inactive state, and the second indication information enables the establishment of a downlink connection between the CU-UPF and the DU, and the data packet of the terminal device is sent to the DU.

[0163] exist Figure 8In the method embodiment shown, the receiving unit 1101 is used to support CU-UPF execution Figure 8 Optionally, the CU-UPF may further include a sending unit 1102 for supporting the CU-UPF to perform Figure 8 Process 803 in the above method embodiment. All relevant contents of each step involved in the above method embodiment can be referred to the functional description of the corresponding functional module, which will not be repeated here.

[0164] The receiving unit 1101 or the sending unit 1102 may be Figure 7 The communication interface 704 in.

[0165] Exemplarily, the DU, CU-CP and CU-UPF in the above-mentioned various device embodiments and the DU, CU-CP and CU-UPF in the method embodiments may completely correspond, and the corresponding modules or units may perform the corresponding steps. For example, the communication module (transceiver) may perform the sending and / or receiving steps in the method embodiment, and other steps except sending and receiving may be performed by the processing unit (processor). The functions of the specific units may refer to the corresponding method embodiments. The sending unit and the receiving unit may form a transceiver unit, and the transmitter and the receiver may form a transceiver to jointly realize the transceiver function; the processor may be one or more.

[0166] Exemplarily, the functions of the above-mentioned DU, CU-CP and CU-UPF can be implemented by a chip, and the processing unit can be implemented by hardware or by software. When implemented by hardware, the processing unit can be a logic circuit, an integrated circuit, etc.; when implemented by software, the processing unit can be a general-purpose processor, which is implemented by reading the software code stored in a storage unit. The storage unit can be integrated in the processor or located outside the processor and exist independently.

[0167] The DU, CU-CP and CU-UPF in the above-mentioned device embodiments completely correspond to the DU, CU-CP and CU-UPF in the method embodiments, and the corresponding modules or units perform the corresponding steps. For example, the sending module (transmitter) method performs the sending steps in the method embodiment, and the receiving module (receiver) performs the receiving steps in the method embodiment. The other steps except sending and receiving can be performed by the processing module (processor). The functions of the specific modules can refer to the corresponding method embodiments. The sending module and the receiving module can form a transceiver module, and the transmitter and the receiver can form a transceiver to jointly realize the transceiver function; the processor can be one or more.

[0168] The division of modules or units in the embodiments of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation. In addition, each functional module in each embodiment of the present application may be integrated into a processor, or may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated modules may be implemented in the form of hardware or in the form of software functional modules. For example, in the embodiments of the present application, the receiving unit and the sending unit may be integrated into the transceiver unit.

[0169] In the method provided in the embodiment of the present application, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can 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 the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device 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 computer-readable storage medium. For example, the computer instructions may be transmitted from a website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or a data center that includes one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital video disc (DVD)), or a semiconductor medium (eg, a solid state drive (SSD)).

[0170] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present application without departing from the scope of the present application. Thus, if these modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A communication method, characterized in that: Applied to the DU in a centralized unit CU-distributed unit DU architecture, the method comprises: The DU receives first control plane information from a centralized unit-control plane CU-CP, where the first control plane information is used to instruct to resume a radio resource control RRC connection of the terminal device; If the DU is the last DU connected before the terminal device enters the inactive state, the DU sends a first indication message to a centralized unit-user plane function network element CU-UPF, wherein the first indication message enables a data packet corresponding to the terminal device to be sent to the DU; If the DU is not the last DU connected before the terminal device enters the inactive state, the DU sends a second indication message to the CU-UPF, and the second indication message enables the CU-UPF to establish a downlink connection with the DU, and the data packet of the terminal device is sent to the DU.

2. The method according to claim 1, characterized in that Before the distributed unit DU receives the first control plane information from the centralized unit-control plane CU-CP, the method further includes: The DU receives an RRC recovery request from the terminal device; The DU sends an initial uplink RRC message to the CU-CP, where the initial uplink RRC message is used to request restoration of the RRC connection of the terminal device.

3. The method according to claim 1 or 2, characterized in that: Before the distributed unit DU receives the first control plane information from the centralized unit-control plane CU-CP, the method further includes: The DU receives a first downlink data packet of a terminal device from the CU-UPF, where a header of the first downlink data packet includes first quality of service flow identifier QFI information, where the first QFI information is used to identify a quality of service QoS flow of the first downlink data packet; When the terminal device is in an inactive state, the DU sends user plane information to the CU-UPF, and the user plane information is used to instruct the CU-UPF to stop sending the second downlink data packet corresponding to the terminal device, the header of the second downlink data packet includes the first QFI information, and the user plane information is also used to instruct the CU-UPF to cache the first downlink data packet and the second downlink data packet.

4. The method according to claim 3, characterized in that The method further comprises: The DU sends second control plane information to the CU-CP, where the second control plane information includes the first QFI information and first paging policy identifier PPI information, and the first QFI information and the first PPI information are used to determine the paging policy of the terminal device.

5. The method according to claim 4, characterized in that The method further comprises: The DU receives a third downlink data packet corresponding to the terminal device from the CU-UPF, wherein a header of the third downlink data packet includes second QFI information and second PPI information, and the second QFI information is different from the first QFI information; The DU sends third control plane information to the CU-CP, where the third control plane information includes the second QFI information and the second PPI information, and the second QFI information and the second PPI information are used to determine a paging policy for the terminal device.

6. The method according to claim 1 or 2, characterized in that: The method further comprises: The DU receives fourth control plane information from the CU-CP, where the fourth control plane information is used to instruct the DU to release air interface resources of the terminal device and retain the connection between the DU and the centralized unit-user plane function network element CU-UPF and the context of the terminal device; The DU releases the air interface resources of the terminal device.

7. The method according to claim 6, characterized in that Before the DU receives the fourth control plane information from the CU-CP, the method further includes: The DU receives fifth control plane information from the CU-CP, where the fifth control plane information is used to indicate a condition for the terminal device to enter an inactive state; The DU sends sixth control plane information to the CU-CP, where the sixth control plane information is used to indicate whether the terminal device meets the conditions for entering an inactive state.

8. A communication method, characterized in that: Applied to a centralized unit-control plane CU-CP in a centralized unit CU-distributed unit DU architecture, the method comprises: The CU-CP sends first control plane information to the distributed unit DU, where the first control plane information is used to restore a radio resource control RRC connection of the terminal device; If the DU is the last DU connected before the terminal device enters the inactive state, the first control plane information includes an uplink port identifier of a centralized unit-user plane function network element CU-UPF; If the DU is not the last DU connected before the terminal device enters the inactive state, the first control plane information includes the uplink port identifier of the CU-UPF and the downlink port information of the last DU serving the terminal device.

9. The method according to claim 8, characterized in that If the DU is not the last DU connected before the terminal device enters the inactive state, the method further includes: The CU-CP sends a terminal device context release message to the last DU connected before the terminal device enters the inactive state, and the terminal device context release message is used to instruct the last DU connected before the terminal device enters the inactive state to release the connection with the CU-UPF and the context of the terminal device.

10. The method according to claim 8 or 9, characterized in that: The method further comprises: The CU-CP receives second control plane information from the DU, where the second control plane information includes first quality of service flow identifier QFI information and first paging policy identifier PPI information, where the first QFI information and the first PPI information are used by the CU-CP to determine a paging policy for a terminal device.

11. The method according to claim 10, characterized in that The method further comprises: The CU-CP receives third control plane information from the DU, where the third control plane information includes second QFI information and second PPI information, where the second QFI information and the second PPI information are used by the CU-CP to determine a paging strategy for the terminal device, and the second QFI information is different from the first QFI information.

12. The method according to claim 8 or 9, characterized in that: The method further comprises: The CU-CP sends fourth control plane information to the DU, where the fourth control plane information is used to instruct the DU to release the air interface resources of the terminal device and retain the connection between the DU and the user plane network element of the core network and the context of the terminal device.

13. The method according to claim 12, characterized in that Before the CU-CP sends the fourth control plane information to the DU, the method further includes: The CU-CP sends fifth control plane information to the DU, where the fifth control plane information is used to indicate a condition for the terminal device to enter an inactive state; The CU-CP receives sixth control plane information from the DU, where the sixth control plane information is used to indicate whether the terminal device meets a condition for entering an inactive state.

14. A communication method, characterized in that: include: If the distributed unit DU receives the first control plane information from the centralized unit-control plane CU-CP, and the DU is the last DU connected before the terminal device enters the inactive state, the centralized unit-user plane function network element CU-UPF receives the first indication information from the DU, the first indication information enables the data packet corresponding to the terminal device to be sent to the DU, and the first control plane information is used to restore the radio resource control RRC connection of the terminal device; If the DU receives the first control plane information from the CU-CP, and the DU is not the last DU connected before the terminal device enters the inactive state, the CU-UPF receives the second indication information from the DU, and the second indication information enables the CU-UPF to establish a downlink connection with the DU, and the data packet of the terminal device is sent to the DU.

15. The method according to claim 14, characterized in that The method further comprises: The CU-UPF sends a first downlink data packet to the DU, where a header of the first downlink data packet carries first quality of service flow identifier QFI information; The CU-UPF receives user plane information from the DU, where the user plane information is used to instruct the CU-UPF to stop sending a second downlink data packet corresponding to the terminal device, where a header of the second downlink data packet includes the first QFI information, and the user plane information is further used to instruct the CU-UPF to cache the first downlink data packet and the second downlink data packet; The CU-UPF stops sending the second downlink data packet, and buffers the first downlink data packet and the second downlink data packet.

16. A communication device, the communication device being the DU in a centralized unit CU-distributed unit DU architecture, characterized in that: include: A receiving unit, configured to receive first control plane information from a centralized unit-control plane CU-CP, wherein the first control plane information is used to instruct to restore a radio resource control RRC connection of a terminal device; A sending unit, configured to send first indication information to a centralized unit-user plane function network element CU-UPF, wherein the first indication information enables a data packet corresponding to the terminal device to be sent to the DU; or The sending unit is used to send second indication information to the CU-UPF, wherein the second indication information enables the CU-UPF to establish a downlink connection with the DU, and the data packet of the terminal device is sent to the DU.

17. The communication device according to claim 16, characterized in that: The receiving unit is also used for: Receiving an RRC recovery request from the terminal device; The sending unit is further used to send an initial uplink RRC message to the CU-CP, where the initial uplink RRC message is used to request restoration of the RRC connection of the terminal device.

18. The communication device according to claim 16 or 17, characterized in that: The receiving unit is also used for: receiving a first downlink data packet of a terminal device from the CU-UPF, wherein a header of the first downlink data packet includes first quality of service flow identifier QFI information, and the first QFI information is used to identify a quality of service QoS flow of the first downlink data packet; When the terminal device is in an inactive state, the sending unit is further used to send user plane information to the CU-UPF, wherein the user plane information is used to instruct the CU-UPF to stop sending a second downlink data packet corresponding to the terminal device, the header of the second downlink data packet includes the first QFI information, and the user plane information is further used to instruct the CU-UPF to cache the first downlink data packet and the second downlink data packet.

19. The communication device according to claim 18, characterized in that: The sending unit is further used for: Sending second control plane information to the CU-CP, where the second control plane information includes the first QFI information and first paging policy identifier PPI information, where the first QFI information and the first PPI information are used to determine the paging policy of the terminal device.

20. The communication device according to claim 19, characterized in that The receiving unit is also used for: receiving, from the CU-UPF, a third downlink data packet corresponding to the terminal device, wherein a header of the third downlink data packet includes second QFI information and second PPI information, and the second QFI information is different from the first QFI information; The sending unit is further used to send third control plane information to the CU-CP, where the third control plane information includes the second QFI information and the second PPI information, and the second QFI information and the second PPI information are used to determine the paging strategy of the terminal device.

21. The communication device according to claim 16 or 17, characterized in that: The receiving unit is also used for: receiving fourth control plane information from the CU-CP, where the fourth control plane information is used to instruct the DU to release air interface resources of the terminal device, and retaining the connection between the DU and the centralized unit-user plane function network element CU-UPF and the context of the terminal device through a storage unit; A processing unit is used to release the air interface resources of the terminal device.

22. The communication device according to claim 21, characterized in that The receiving unit is also used for: receiving fifth control plane information from the CU-CP, where the fifth control plane information is used to indicate a condition for the terminal device to enter an inactive state; The sending unit is further used to send sixth control plane information to the CU-CP, where the sixth control plane information is used to indicate whether the terminal device meets the conditions for entering an inactive state.

23. A communication device, the communication device being a centralized unit-control plane CU-CP in a centralized unit CU-distributed unit DU architecture, characterized in that: include: A sending unit, configured to send first control plane information to the distributed unit DU, wherein the first control plane information is used to restore a radio resource control RRC connection of a terminal device; If the DU is the last DU connected before the terminal device enters the inactive state, the first control plane information includes an uplink port identifier of a centralized unit-user plane function network element CU-UPF; If the DU is not the last DU connected before the terminal device enters the inactive state, the first control plane information includes the uplink port identifier of the CU-UPF and the downlink port information of the last DU serving the terminal device.

24. The communication device according to claim 23, characterized in that If the DU is not the last DU connected before the terminal device enters the inactive state, the sending unit is further used to: A terminal device context release message is sent to the last DU connected before the terminal device enters the inactive state, wherein the terminal device context release message is used to instruct the last DU connected before the terminal device enters the inactive state to release the connection with the CU-UPF and the context of the terminal device.

25. The communication device according to claim 23 or 24, characterized in that: Also included is a receiving unit, configured to: Second control plane information is received from the DU, where the second control plane information includes first quality of service flow identifier QFI information and first paging policy identifier PPI information, where the first QFI information and the first PPI information are used by the CU-CP to determine a paging policy for the terminal device.

26. The communication device according to claim 25, characterized in that The receiving unit is also used for: Receive third control plane information from the DU, the third control plane information including second QFI information and second PPI information, the second QFI information and the second PPI information are used by the CU-CP to determine a paging strategy for the terminal device, and the second QFI information is different from the first QFI information.

27. The communication device according to claim 23 or 24, characterized in that: The sending unit is also used for: The CU-CP sends fourth control plane information to the DU, where the fourth control plane information is used to instruct the DU to release the air interface resources of the terminal device and retain the connection between the DU and the user plane network element of the core network and the context of the terminal device.

28. The communication device according to claim 27, characterized in that The sending unit is also used for: Sending fifth control plane information to the DU, where the fifth control plane information is used to indicate a condition for the terminal device to enter an inactive state; The receiving unit is also used to receive sixth control plane information from the DU, and the sixth control plane information is used to indicate whether the terminal device meets the conditions for entering an inactive state.

29. A communication device, the communication device being a centralized unit-user plane function network element CU-UPF, characterized in that: include: A receiving unit, configured to receive first indication information from a distributed unit DU if the distributed unit DU receives first control plane information from a centralized unit-control plane CU-CP, and the DU is the last DU connected before the terminal device enters an inactive state, wherein the first indication information enables a data packet corresponding to the terminal device to be sent to the DU, and the first control plane information is used to restore a radio resource control RRC connection of the terminal device; or A receiving unit, configured to receive second indication information from the DU if the DU receives first control plane information from the CU-CP, and the DU is not the last DU connected before the terminal device enters an inactive state, wherein the second indication information enables the CU-UPF to establish a downlink connection with the DU, and the data packet of the terminal device is sent to the DU.

30. The communication device according to claim 29, characterized in that Also includes a sending unit, for: Sending a first downlink data packet to the DU, wherein a header of the first downlink data packet carries first quality of service flow identifier QFI information; The receiving unit is used to receive user plane information from the DU, the user plane information is used to instruct the CU-UPF to stop sending a second downlink data packet corresponding to the terminal device, the header of the second downlink data packet includes the first QFI information, and the user plane information is also used to instruct the CU-UPF to cache the first downlink data packet and the second downlink data packet; The sending unit is used for stopping sending the second downlink data packet and buffering the first downlink data packet and the second downlink data packet through the buffer unit.

31. A communication device, characterized in that: The communication device includes a transceiver, a memory and a processor, wherein the processor is coupled to the memory; The memory is used to store computer-executable instructions. When the communication device is running, the processor executes the computer-executable instructions to enable the communication device to perform the method of any one of claims 1-7, claims 8-13, or claims 14-15.

32. A computer-readable storage medium, characterized in that: The method comprises instructions which, when executed on a computer, cause the computer to execute the method according to any one of claims 1 to 7, claims 8 to 13, or claims 14 to 15.

33. A communication system, characterized in that: The communication system comprises: the communication device described in any one of claims 16-22, the communication device described in any one of claims 23-28, and the communication device described in any one of claims 29-30.

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