CN113939044A

CN113939044A - Communication method and device

Info

Publication number: CN113939044A
Application number: CN202010606037.4A
Authority: CN
Inventors: 王亚鑫; 李岩
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-06-29
Filing date: 2020-06-29
Publication date: 2022-01-14
Also published as: WO2022001894A1

Abstract

The embodiment of the application provides a communication method and device, relates to the field of communication, and can avoid loss of downlink data when terminal equipment is in communication with a network side. The method comprises the following steps: the DU receives first control plane information from the CU-CP, wherein the first control plane information is used for indicating the recovery of the RRC connection of the terminal equipment; if the DU is the last DU connected before the terminal equipment enters the non-activated state, the DU sends first indication information to the CU-UPF, and the first indication information enables a data packet corresponding to the terminal equipment to be sent to the DU; and if the DU is not the last DU connected before the terminal equipment enters the non-activated state, the DU sends second indication information to the CU-UPF, the second indication information enables the CU-UPF and the DU to be established with downlink connection, and a data packet of the terminal equipment is sent to the DU. The embodiment of the application is applied to a 5G communication system.

Description

Communication method and device

Technical Field

The present application relates to the field of communications, and in particular, to a communication method and apparatus.

Background

In the fifth generation (5)^thgeneration, 5G) mobile communication system, by splitting a Radio Access Network (RAN) into a centralized processing node (CU) and a distributed processing node (DU), a base station can be adjusted more flexibly. Wherein, CU can also be called gNB-CU, and DU can also be called gNB-DU. Further, the CU may be divided into a control plane (CU control plane, CU-CP) of the centralized processing node and a user plane (CU user plane, CU-UP) of the centralized processing node according to functions. Wherein CU-CP may also be referred to asFor gNB-CU-CP, CU-UP may also be referred to as gNB-CU-UP.

With the maturity of CU/DU separation technology, multi-access edge computing (MEC) and a sunken User Plane Function (UPF) network element (a sunken UPF network element (abbreviated as UPF) refers to a UPF deployed in the same physical machine room as a gNB-CU) are widely deployed, and the combined deployment of the gNB-CU, the UPF and the MEC may become a mainstream. In this scenario, since the gNB-CU is already deployed in the same physical machine room as the sunk UPF, the UPF and the gNB-CU-UP may be combined into one network element finally due to the consideration of factors such as reducing the number of data plane transmission hops, saving the cost, and terminating the data plane security node in the core network.

In the scenario of combining the UPF and the gNB-CU-UP, how the terminal device communicates with the network side does not have a corresponding solution at present.

Disclosure of Invention

The embodiment of the application provides a communication method and a communication device, which are applied to a combined setting scene of UPF and CU-UP and can avoid the loss of downlink data when terminal equipment is communicated with a network side.

In a first aspect, an embodiment of the present application provides a communication method applied to a centralized unit CU-distributed unit DU architecture, where the method includes: the DU receives first control plane information from the centralized unit-control plane CU-CP, the first control plane information being used to instruct recovery of 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 DU sends first indication information to a centralized unit-user plane function (CU-UPF) element, where the first indication information enables a data packet corresponding to the terminal device to be sent to the DU; and if the DU is not the last DU connected before the terminal equipment enters the non-activated state, the DU sends second indication information to the CU-UPF, the second indication information enables the CU-UPF and the DU to be established with downlink connection, and a data packet of the terminal equipment is sent to the DU. It should be noted that the DU may send the first indication information to the CU-UPF, or the DU may send the second indication information to the CU-UPF, that is, the first indication information or the second indication information is sent alternatively.

Based on the method provided by the embodiment of the application, if the DU is the last DU connected before the terminal equipment enters the non-activated state, the DU sends first indication information to the CU-UPF, and the CU-UPF is enabled to send the data packet corresponding to the terminal equipment to the DU; and if the DU is not the last DU connected before the terminal equipment enters the non-activated state, the DU sends second indication information to the CU-UPF, so that the CU-UPF can establish downlink connection with the DU and send a data packet of the terminal equipment to the DU. After the DU acquires the data packet corresponding to the terminal equipment from the CU-UPF, the data packet can be sent to the terminal equipment through the air interface resource, and the terminal equipment is prevented from losing the downlink data in the non-activated state.

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 comprises: the DU receives an RRC recovery request from the terminal equipment; the DU transmits an initial uplink Radio Resource Control (RRC) message to the CU-CP, the initial uplink RRC message requesting to resume RRC connection of the terminal device. That is, after receiving the RRC recovery request of the terminal device, the DU sends an initial uplink RRC message to the CU-CP, where the DU may be the last DU connected before the terminal device enters the inactive state (i.e., DU handover does not occur), or may be another DU (i.e., DU handover occurs).

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 comprises: the DU receives a first downlink packet of the terminal equipment from the CU-UPF, wherein the packet header of the first downlink packet comprises first quality of service (QoS) flow identification (QFI) information, and the first QFI information is used for identifying QoS (QoS) flow of the first downlink packet; and when the terminal equipment is in an inactive state, the DU sends user plane information to the CU-UPF, wherein the user plane information is used for indicating the CU-UPF to stop sending a second downlink data packet corresponding to the terminal equipment, the packet header of the second downlink data packet comprises first QFI information, and the user plane information is also used for indicating the CU-UPF to cache the first downlink data packet and the second downlink data packet.

Based on the method provided by the embodiment of the application, after the DU receives the downlink data packet from the CU-UPF, the CU-UPF can be informed of stopping issuing and caching the corresponding downlink data packet through the user plane information. Because the DU has no function of caching data, the CU-UPF is instructed to stop sending and cache the corresponding downlink data packet, so that data packet loss can be avoided, and communication resources occupied by sending useless data to the DU by the CU-UPF can be avoided.

In one possible implementation, the method further includes: the DU transmits second control plane information to the CU-CP, the second control plane information including first QFI information and first Paging Policy Identifier (PPI) information, the first QFI information and the first PPI information being used for determining a paging policy of the terminal device.

In one possible implementation, the method further includes: the DU receives a third downlink data packet corresponding to the terminal equipment from the CU-UPF, the packet header of the third downlink data packet comprises 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, wherein the third control plane information comprises second QFI information and second PPI information, and the second QFI information and the second PPI information are used for determining a paging strategy of the terminal device. The CU-CP may determine a Paging policy again according to second PPI information in the third control plane information, and if the priority of the Paging policy determined according to the first PPI information is lower than the priority of the Paging policy determined according to the second PPI information, the CU-CP may update the Paging policy of the terminal device; if the priority of the Paging policy determined according to the first PPI information is not lower than (higher than or equal to) the priority of the Paging policy determined according to the second PPI information, the CU-CP may still perform Paging on the terminal device according to the Paging policy determined by the first PPI information.

In one possible implementation, the method further includes: the DU receives fourth control plane information from the CU-CP, wherein the fourth control plane information is used for indicating the DU to release air interface resources of the terminal equipment and reserving the connection between the DU and a centralized unit-user plane functional network element CU-UPF and the context of the terminal equipment; the DU releases the air interface resources of the terminal device.

Based on the method provided by the embodiment of the application, when the CU-CP triggers the UE to enter the Inactive state, the CU-CP can indicate the DU to release the relevant air interface resource, and the user interface connection with the closed network element CU-UPF and the relevant UE context are reserved, the CU-UPF does not sense the process, and the process can be distinguished from the process of initiating paging by detecting downlink data by UPF (equivalent to CU-UPF) under RRC Idle, so that the problem that the prior art cannot support the RRC Inactive technology is solved.

In a possible implementation manner, 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, wherein the fifth control plane information is used for indicating the condition that the terminal equipment enters the inactive state; the DU sends sixth control plane information to the CU-CP, the sixth control plane information indicating whether the terminal device satisfies a condition for entering an inactive state.

In a second aspect, an embodiment of the present application provides a communication method applied to a centralized unit-control plane CU-CP in a centralized unit CU-distributed unit DU architecture, the method including: the CU-CP sends first control plane information to the distributed unit DU, wherein the first control plane information is used for recovering the Radio Resource Control (RRC) connection of the terminal equipment; if the DU is the last DU connected before the terminal equipment enters the inactive state, the first control plane information comprises an uplink port identifier of a centralized unit-user plane function network element CU-UPF; and if the DU is not the last DU connected before the terminal equipment enters the inactive state, the first control plane information comprises the uplink port identification of the CU-UPF and the downlink port information of the last DU serving the terminal equipment.

Based on the method provided by the embodiment of the present application, the CU-CP may send the first control plane information to the DU to recover the RRC connection of the terminal device. And if the DU switching does not occur, the DU can acquire the data packet corresponding to the terminal equipment from the CU-UPF according to the uplink port identifier of the CU-UPF. If the DU switching occurs, the DU may obtain a data packet corresponding to the terminal device (a data packet delivered by the core network when the terminal device is in the inactive period) 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. Then, the DU may send the data packet to the terminal device through the air interface resource, so as to prevent the terminal device from losing its downlink data in the inactive state.

In a possible implementation manner, if the DU is not the last DU connected before the terminal device enters the inactive state, the method further includes: and the CU-CP sends a terminal equipment context release message to the last DU connected before the terminal equipment enters the inactive state, wherein the terminal equipment context release message is used for indicating the last DU connected before the terminal equipment 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 equipment.

In one possible implementation, the method further includes: the CU-CP receives second control plane information from the DU, wherein the second control plane information comprises first QFI information and first PPI information, and the first QFI information and the first PPI information are used for the CU-CP to determine a paging strategy for the terminal equipment.

In one possible implementation, the method further includes: the CU-CP receives 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 being used for the CU-CP to determine a paging strategy for the terminal device, the second QFI information being different from the first QFI information, the second PPI information being different from the first PPI information.

In one possible implementation, the method further includes: and the CU-CP sends fourth control plane information to the DU, wherein the fourth control plane information is used for indicating the DU to release air interface resources of the terminal equipment and reserving the connection between the DU and a user plane network element of the core network and the context of the terminal equipment.

In one possible implementation, 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, wherein the fifth control plane information is used for indicating the condition that the terminal equipment enters the non-activated state; the CU-CP receives sixth control plane information from the DU, the sixth control plane information indicating whether the terminal device satisfies a condition for entering an inactive state.

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 first indication information from a distributed unit DU, wherein the DU is the last DU connected before a terminal device enters an inactive state, and a data packet corresponding to the terminal device is enabled by the first indication information and is sent to the DU; or the CU-UPF receives second indication information from the DU, the DU is not the last DU connected before the terminal device enters the inactive state, the second indication information enables the CU-UPF to establish a downlink connection with the DU, and a data packet of the terminal device is sent to the DU.

Based on the method provided by the embodiment of the application, if the DU is the last DU connected before the terminal equipment enters the non-activated state, the CU-UPF receives first indication information from the DU, and the CU-UPF is enabled by the first indication information to send the data packet corresponding to the terminal equipment to the DU; and if the DU is not the last DU connected before the terminal equipment enters the non-activated state, the CU-UPF receives second indication information from the DU, and the second indication information enables the CU-UPF to establish downlink connection with the DU and sends a data packet of the terminal equipment to the DU. After the DU acquires the data packet corresponding to the terminal equipment from the CU-UPF, the data packet can be sent to the terminal equipment through the air interface resource, and the terminal equipment is prevented from losing the downlink data in the non-activated state.

In one possible implementation, the method further includes: the CU-UPF sends a first downlink data packet to the DU, and the packet header of the first downlink data packet carries first service quality flow identification QFI information; the CU-UPF receives user plane information from the DU, the user plane information is used for indicating the CU-UPF to stop sending a second downlink data packet corresponding to the terminal equipment, a packet header of the second downlink data packet comprises first QFI information, and the user plane information is also used for indicating the CU-UPF to cache the first downlink data packet and the second downlink data packet; and the CU-UPF stops sending the second downlink data packet corresponding to the terminal equipment and caches the first downlink data packet and the second downlink data packet.

In a fourth aspect, an embodiment of the present application provides a communication apparatus, which is a centralized unit CU-distributed unit DU architecture, including: a receiving unit configured to receive first control plane information from the centralized unit-control plane CU-CP, the first control plane information being used to instruct a radio resource control, RRC, connection of the terminal device to resume; a sending unit, configured to send first indication information to a centralized unit-user plane function network element CU-UPF, where the first indication information enables a data packet corresponding to a terminal device to be sent to a DU; or, the sending unit is configured to send second indication information to the CU-UPF, where the second indication information enables 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 one possible implementation, the receiving unit is further configured to: receiving an RRC recovery request from a terminal device; and the sending unit is further used for sending an initial uplink RRC message to the CU-CP, wherein the initial uplink RRC message is used for requesting to recover the RRC connection of the terminal equipment.

In one possible implementation, the receiving unit is further configured to: receiving a first downlink data packet of the terminal equipment from the CU-UPF, wherein the packet header of the first downlink data packet comprises first QFI (quality of service) flow identification QFI (quality of service) information, and the first QFI information is used for identifying a QoS (quality of service) flow of the first downlink data packet; and when the terminal equipment is in an inactive state, the sending unit is further used for sending user plane information to the CU-UPF, wherein the user plane information is used for indicating the CU-UPF to stop sending a second downlink data packet corresponding to the terminal equipment, the packet header of the second downlink data packet comprises the first QFI information, and the user plane information is also used for indicating the CU-UPF to cache the first downlink data packet and the second downlink data packet.

In a possible implementation manner, the sending unit is further configured to: and sending second control plane information to the CU-CP, wherein the second control plane information comprises the first QFI information and the first paging strategy identification PPI information, and the first QFI information and the first PPI information are used for determining the paging strategy of the terminal equipment.

In one possible implementation, the receiving unit is further configured to: receiving a third downlink data packet corresponding to the terminal device from the CU-UPF, wherein a packet header of the third downlink data packet comprises second QFI information and second PPI information, and the second QFI information is different from the first QFI information; and the sending unit is further used for sending third control plane information to the CU-CP, wherein the third control plane information comprises second QFI information and second PPI information, and the second QFI information and the second PPI information are used for determining a paging strategy of the terminal device.

In one possible implementation, the receiving unit is further configured to: receiving fourth control plane information from the centralized unit-control plane CU-CP, wherein the fourth control plane information is used for indicating the DU to release air interface resources of the terminal equipment, and reserving the connection between the DU and the centralized unit-user plane functional network element CU-UPF and the context of the terminal equipment through a storage unit; and the processing unit is used for releasing the air interface resources of the terminal equipment.

In one possible implementation, the receiving unit is further configured to: receiving fifth control plane information from the CU-CP, wherein the fifth control plane information is used for indicating the condition that the terminal equipment enters the non-activated state; and the sending unit is further used for sending sixth control plane information to the CU-CP, wherein the sixth control plane information is used for indicating whether the terminal equipment meets the condition of entering the inactive state or not.

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

In a possible implementation manner, if the DU is not the last DU connected before the terminal device enters the inactive state, the sending unit is further configured to: and sending a terminal equipment context release message to the last DU connected before the terminal equipment enters the inactive state, wherein the terminal equipment context release message is used for indicating the last DU connected before the terminal equipment 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 equipment.

In a possible implementation manner, the method further includes a receiving unit, configured to: and receiving second control plane information from the DU, wherein the second control plane information comprises first QFI information and first PPI information, and the first QFI information and the first PPI information are used for the CU-CP to determine a paging strategy for the terminal equipment.

In one possible implementation, the receiving unit is further configured to: receiving 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 being used by the CU-CP to determine a paging strategy for the terminal device, the second QFI information being different from the first QFI information, the second PPI information being different from the first PPI information.

In a possible implementation manner, the sending unit is further configured to: and the CU-CP sends fourth control plane information to the DU, wherein the fourth control plane information is used for indicating the DU to release air interface resources of the terminal equipment and reserving the connection between the DU and a user plane network element of the core network and the context of the terminal equipment.

In a possible implementation manner, the sending unit is further configured to: sending fifth control plane information to the DU, wherein the fifth control plane information is used for indicating the condition that the terminal equipment enters the non-activated state; and the receiving unit is further configured to receive sixth control plane information from the DU, where the sixth control plane information is used to indicate whether the terminal device satisfies a condition for entering the inactive state.

In a sixth aspect, an embodiment of the present application provides a communication apparatus, where the communication apparatus is a centralized unit-user plane function network element CU-UPF, and the communication apparatus includes: the terminal equipment comprises a receiving unit, a sending unit and a sending unit, wherein the receiving unit is used for receiving first indication information from a distributed unit DU, the DU is the last DU connected before the terminal equipment enters an inactive state, and a data packet corresponding to the first indication information enabling the terminal equipment is sent to the DU; or, the receiving unit is configured to receive second indication information from the DU, where the DU is not the last DU connected before the terminal device enters the inactive state, the second indication information enables establishment of a downlink connection between the CU-UPF and the DU, and a data packet of the terminal device is sent to the DU.

In a possible implementation manner, the method further includes a sending unit, configured to: sending a first downlink data packet to the DU, wherein the packet header of the first downlink data packet carries first service quality flow identification QFI information; the receiving unit is used for receiving user plane information from the DU, the user plane information is used for indicating the CU-UPF to stop sending a second downlink data packet corresponding to the terminal equipment, a packet header of the second downlink data packet comprises first QFI information, and the user plane information is also used for indicating 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 corresponding to the terminal equipment and caching the first downlink data packet and the second downlink data packet through the cache unit.

In a seventh aspect, a communication apparatus, which may be a DU, includes: a processor and a memory; the memory is for storing computer executable instructions, and the processor is for executing the computer executable instructions stored by the memory to cause the apparatus to perform the method of any one of the first aspects as described above.

In an eighth aspect, there is provided a communication apparatus, which may be a CU-CP, comprising: a processor and a memory; the memory is used for storing computer-executable instructions, and the processor executes the computer-executable instructions stored by the memory to cause the apparatus to perform the method according to any one of the second aspects.

In a ninth aspect, there is provided a communication device, which may be a CU-UPF, comprising: a processor and a memory; the memory is for storing computer executable instructions, and the processor is for executing the computer executable instructions stored by the memory to cause the apparatus to perform the method of any one of the above third aspects.

A tenth aspect provides a computer-readable storage medium having stored therein instructions, which when run on a computer, cause the computer to perform the method of any of the first to third aspects described above.

In an eleventh aspect, there is provided a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of any of the first to third aspects described above.

In a twelfth aspect, there is provided circuitry comprising processing circuitry configured to perform the method of any of the first to third aspects as described above.

In a thirteenth aspect, a chip is provided, the chip comprising a processor, the processor being coupled to a memory, the memory storing program instructions, which when executed by the processor implement the method of any of the first to third aspects described above.

In a fourteenth aspect, there is provided a communication system comprising the communication apparatus of any one of the above fourth aspect, the communication apparatus of any one of the fifth aspect, and the communication apparatus of any one of the sixth aspect.

Drawings

Fig. 1 is a schematic diagram of a network architecture in a CU/DU separation scenario according to an embodiment of the present disclosure;

fig. 2A is a schematic diagram of a protocol stack of a gNB-DU and a gNB-CU-CP according to an embodiment of the present disclosure;

FIG. 2B is a diagram of a gNB-DU and gNB-CU-UP protocol stack according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a distribution of a gNB-DU, a gNB-CU-CP, and a gNB-CU-UP provided in an embodiment of the present application;

fig. 4 is a schematic diagram of a network architecture in a combined scenario of UPF and gNB-CU-UP according to an embodiment of the present application;

fig. 5 is a schematic diagram of a network architecture in another scenario of a combination of UPF and gNB-CU-UP according to an embodiment of the present application;

fig. 6A is a schematic diagram of a control plane protocol stack architecture in a scenario where a gbb-CU-CP and a UPF are jointly provided in the present embodiment;

fig. 6B is a schematic diagram of a user plane protocol stack architecture of a combined scenario of a gNB-CU-CP and a UPF according to an embodiment of the present disclosure;

FIG. 7 is a schematic structural diagram of a DU, CU-CP or CU-UPF according to an embodiment of the present application;

fig. 8 is a schematic diagram of a signal interaction provided in an embodiment of the present application;

fig. 9 is a schematic structural diagram of another DU provided in an embodiment of the present application;

FIG. 10 is a schematic structural diagram of another CU-CP provided in an embodiment of the present application;

FIG. 11 is a schematic structural diagram of another CU-UPF according to an embodiment of the present application.

Detailed Description

For clarity and conciseness of the following description of the various embodiments, a brief introduction to related concepts or technologies is first presented:

the CU/DU separation technology is an important characteristic in 5G, can adjust base station networking more flexibly, has good benefits on load balancing and resource maximum utilization, and has better support on solving tidal effect, deploying double connections, edge calculation, service distribution and intelligent operation and maintenance.

As shown in fig. 1, a schematic diagram of a network architecture in a CU/DU separation scenario is shown. In the CU/DU split scenario, the gNB can be divided into gNB-CU-CP, gNB-CU-UP, and gNB-DU. The gNB-CU-CP may communicate with the gNB-CU-UP through an E1 interface, the gNB-CU-CP may communicate with the gNB-DU through an F1-C interface, and the gNB-CU-UP may communicate with the gNB-DU through an F1-U interface. The terminal equipment can access the network through the gNB-DU. The gNB-CU-CP may communicate with an access and mobility management function (AMF) network element through a Next generation Network (NG) 2 interface (N2 for short), the AMF may communicate with a Session Management Function (SMF) network element through an N11 interface (N11 for short), the SMF may communicate with a UPF network element through an N4 interface (N4 for short), the UPF network element may access a data network (network, DN) through an N6 interface (N6 for short), and the UPF network element may communicate with the gNB-UP-CU through an N3 interface (N3 for short).

The AMF is responsible for access and mobility management functions, and may receive non-access stratum (NAS) signaling (including Session Management (SM) signaling) of the terminal device and related signaling of the access network device, and complete a registration process of a user, forwarding of the SM signaling, and mobility management. The SMF is responsible for a session management function, and completes procedures such as establishment, release, update, and the like related to a Protocol Data Unit (PDU) session.

A terminal device may also be referred to as a terminal, a terminal may be a wireless terminal or a wired terminal, a wireless terminal may be a device that provides voice and/or data connectivity to a user, a handheld device having a wireless connection function, or other processing device connected to a wireless modem. A wireless terminal may communicate with one or more core networks via a Radio Access Network (RAN), and the wireless terminal may be a mobile terminal, such as a mobile phone (or referred to as a "cellular" phone) and a computer having a mobile terminal, for example, the wireless terminal may be a portable, pocket, hand-held, computer-included, or vehicle-mounted mobile device, and may also be 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 the like. A wireless terminal may also be referred to as a system, a subscriber unit (subscriber unit), a subscriber station (subscriber station), a mobile station (mobile), a remote station (remote station), a remote terminal (remote terminal), an access terminal (access terminal), a user agent (user agent), a user equipment or a device (user equipment). The wireless terminal may also be a desktop computer, a laptop 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., and is not limited herein.

As shown in fig. 2A, in the CU/DU separation architecture, RRC and Packet Data Convergence Protocol (PDCP) protocol stacks may be distributed in a gNB-CU-CP (CU-CP), Radio Link Control (RLC), Medium Access Control (MAC), and physical layer (PHY) protocol stacks may be distributed in a gNB-DU (DU). As shown in FIG. 2B, the Service Data Adaptation Protocol (SDAP) and PDCP protocol stacks may be distributed over gNB-CU-UP (CU-UP).

As shown in fig. 3, the gNB-DUs can be deployed in a distributed manner, the gNB-CU-CPs and the gNB-CU-UPs can be deployed in a centralized manner, and one gNB-CU-CP can control a plurality of gNB-CU-UPs which can be flexibly grouped and distributed in different areas to serve the gNB-DUs in different areas. One gNB-CU-UP may be connected with multiple gNB-DUs, and one gNB-DU may be connected with one or more gNB-CU-UP.

With the maturity of CU/DU separation technology, the widespread deployment of MEC and sunken 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 embodiments of the present application is only a naming method, and does not exclude defining other possible names in the existing or future protocol to replace the above names. As shown in fig. 4, CU-UPF may be managed by SMF for unified scheduling. The CU-UPF can communicate with the gNB-DU through an F1-U interface, the CU-UPF can access the DN through an N6 interface, the administrative authority of the gNB-CU-CP on the gNB-CU-UP (namely the CU-UPF) can be cancelled (the original E1 interface is cancelled), or only partial authority and system structure which do not influence the safety can be reserved.

In the scenario of combined UPF and gNB-CU-UP, how the terminal device communicates with the network side, no corresponding solution exists at present. For example, when the terminal device enters the RRC Inactive state (RRC Inactive/RRC _ Inactive), since the gNB-CU-UP and the UPF are combined to be a network element (i.e., CU-UPF), if the downlink data origination Paging (Paging) is detected by the gNB-CU-UP (equivalent to the CU-UPF), there is no difference from the downlink data origination Paging (Paging) detected by the UPF (equivalent to the CU-UPF) in the RRC Idle state (RRC Idle/RRC Idle), and the support for the RRC Inactive technology is lost. Here, RRC _ INACTIVE may be considered as an intermediate state between RRC _ IDLE and RRC CONNECTED (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.

The embodiment of the application provides a communication method, which is applied to a CU-UP and UPF combined scene (UPF and CU-UP are combined into CU-UPF), wherein the gNB-CU-CP can indicate the gNB-DU to release relevant air interface resources, and the user interface connection and the relevant UE context of a combined network element CU-UPF are reserved, the CU-UPF does not sense the process, and can be distinguished from the process of initiating paging by detecting downlink data by UPF (equivalent to CU-UPF) under RRC Idle, so that the problem that the prior art cannot support the RRC Inactive technology is solved.

Furthermore, after the gNB-DU detects the downlink data packet from the CU-UPF, the CU-UPF can be informed of stopping issuing the corresponding downlink data packet through the user plane information, and the downlink data packet is cached. Because the DU has no function of caching data, the CU-UPF is instructed to stop sending and cache the corresponding downlink data packet, so that data packet loss can be avoided, and communication resources occupied by sending useless data to the DU by the CU-UPF can be avoided.

If the DU is the last DU connected before the terminal equipment enters the non-activated state, the DU can send first indication information to the CU-UPF, and the first indication information enables a data packet corresponding to the terminal equipment 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 second indication information to the CU-UPF, the second indication information enables the CU-UPF to establish a downlink connection with the DU, and a data packet of the terminal device is sent to the DU. Therefore, after the DU acquires the data packet corresponding to the terminal device from the CU-UPF, the data packet can be sent to the terminal device through the air interface resource, and the terminal device is prevented from losing the downlink data in the inactive state. It should be noted that the DU may send the first indication information to the CU-UPF, or the DU may send the second indication information to the CU-UPF, that is, the first indication information or the second indication information is sent alternatively.

The communication method and the device provided by the embodiment of the application can be applied to a 5G mobile communication system or a New Radio (NR) system and the like. The technical scheme provided by the application can also be applied to future communication systems, such as a sixth generation mobile communication system. The communication system may be a 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 networks that are evolved in the future, which is not limited in this application.

The network architecture applicable to the embodiment of the present application is shown in fig. 5, where one gNB-CU-CP may control multiple gNB-DUs. When the UE has no downlink service data, the UE can enter an inactive state, namely release the transmission resources of the air port, but reserve the related resources of the NG-U. When downlink data arrives from the core network, 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 downlink data of the core network arrives, if the UE moves (moving) from the service range of one gNB-DU to the service range of another gNB-DU within the control range of the gNB-CU-CP, that is, a DU handover occurs, the UE may 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 connected before the UE enters the inactive state, that is, DU handover does not occur, and the UE resumes the connection with the gNB-DU.

In addition, the descriptions of the other network elements in fig. 5 may refer to the descriptions related to fig. 1 and fig. 4, which are not described herein again. Of course, the network architecture related to fig. 5 may also include other network elements, such as a Unified Data Management (UDM) network element, a Policy Control Function (PCF) network element, an authentication server function (AUSF) network element, a network open function (NEF) network element/network function storage function (NRF) network element/Network Slice Selection Function (NSSF), a Unified Data Repository (UDR) or a network storage function (NRF), and the like, which are not limited in particular.

It should be noted that the names of the interfaces between the network elements and the network elements in fig. 5 are only an example, and the names of the interfaces between the network elements and the network elements in the specific implementation may be other names, which is not specifically limited in this embodiment of the present application.

Fig. 6A is a schematic diagram of a control plane protocol stack architecture in a scenario combining a gNB-CU-CP and a UPF. Wherein, the peer protocol layers between the UE and the DU comprise an RLC layer, an MAC layer and a PHY. The peer-to-peer protocol layers between the UE and the CU-CP include an RRC layer and a PDCP layer. The peering protocol layer between the UE and the AMF includes a non-access stratum (NAS) layer. The peer-to-peer protocol layer between the AMF and SMF includes the NAS layer. Since the control of the CU-UPF by the gNB-CU-CP is cancelled, the PDCP and SDAP Config messages related to the quality of service (QoS) Flow (Flow) control and security can be finally issued to the CU-UPF through the path of the CU-CP- > AMF- > SMF- > CU-UPF at the control plane.

As shown in fig. 6B, a schematic diagram of a user plane protocol stack architecture for a combined scenario of a gNB-CU-CP and a UPF. Wherein, the peer protocol layer between the UE and the CU-UPF comprises an SDAP layer and a PDCP layer, and the peer protocol layer between the UE and the UPF comprises a Protocol Data Unit (PDU) layer (layer). The CU-UPF is connected via a three-layer protocol either directly to the DN (not shown in fig. 6B) or to the PDU Session Anchor (PSA) of the UPF. The peer protocol layers between the CU-UPF and the UPF include a General Packet Radio Service (GPRS) tunneling protocol user plane (GTP-U), a User Datagram Protocol (UDP)/Internet Protocol (IP) layer, an L2 layer, and an L1 layer.

For convenience of description, the gNB-DU, gNB-CU-CP, and gNB-CU-UP will be referred to hereinafter as DU, CU-CP, and CU-UP, respectively. It should be noted that CU-CP (gNB-CU-CP), CU-UP (gNB-CU-UP), and DU (gNB-DU) in the embodiments of the present application are only naming manners, and it is not excluded that other possible naming is defined in the existing or future protocol to replace the above-mentioned naming.

The DU, CU-CP or CU-UPF in the embodiments of the present application may be implemented by the communication device in FIG. 7. Fig. 7 is a schematic diagram illustrating a hardware structure of a communication device according to an embodiment of the present application. The communication device 700 includes at least one processor 701, communication lines 702, memory 703 and at least one communication interface 704.

The processor 701 may be a general-purpose Central Processing Unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more ics for controlling the execution of programs in accordance with the present disclosure.

The communication link 702 may include a path for communicating information between the aforementioned components.

Communication interface 704, using any transceiver or the like, may be used to communicate with other devices or communication networks, such as an ethernet, a Radio Access Network (RAN), a Wireless Local Area Network (WLAN), etc.

The memory 703 may be, but is not limited to, a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a Random Access Memory (RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disk read-only memory (CD-ROM) or other optical disk storage, optical disk storage (including compact disk, laser disk, optical disk, digital versatile disk, blu-ray disk, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. The memory may be separate and coupled to the processor via a communication line 702. The memory may also be integral to the processor.

The memory 703 is used for storing computer-executable instructions for executing the present invention, and is controlled by the processor 701 to execute. The processor 701 is configured to execute computer-executable instructions stored in the memory 703, so as to implement the communication method provided by the following embodiments of the present application.

Optionally, the computer-executable instructions in the embodiments of the present application may also be referred to as application program codes, which are not specifically limited in the embodiments of the present application.

In particular implementations, processor 701 may include one or more CPUs such as CPU0 and CPU1 of fig. 7 for one embodiment.

In particular implementations, communication device 700 may include multiple processors, such as processor 701 and processor 705 in fig. 7, for one embodiment. Each of these processors may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. A processor herein may refer to one or more devices, circuits, and/or processing cores for processing data (e.g., computer program instructions).

The communication method provided by the embodiment of the present application will be specifically described below with reference to the accompanying drawings. It should be noted that names of network elements, names of messages between network elements, names of parameters in messages, and the like in the following embodiments of the present application are only examples, and may also be other names in specific implementations, and this is not limited in this embodiment of the present application.

In the description of the present application, "at least one" means one or more, "a plurality" means two or more than two, unless otherwise specified. In addition, in order to facilitate clear description of technical solutions of the embodiments of the present application, in the embodiments of the present application, terms such as "first" and "second" are used to distinguish the same items or similar items having substantially the same functions and actions. Those skilled in the art will appreciate that the terms "first," "second," etc. do not denote any order or quantity, nor do the terms "first," "second," etc. denote any order or importance.

In this embodiment of the present application, the control plane information (e.g., the first to fifth control plane information) refers to information used for interaction between the DU and the CU-CP, and the control plane information may also be referred to by other names, which is not limited in this application.

For the sake of understanding, the communication method provided by the embodiments of the present application is specifically described below with reference to the accompanying drawings.

As shown in fig. 8, an embodiment of the present application provides a communication method, including:

801. the CU-CP transmits control plane information (fourth control plane information) to the DU.

The fourth control plane information is used to instruct the DU to release air interface resources of the terminal device, and reserve 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. Illustratively, the fourth control plane information may be a UE Context Release Command, which contains an RRC Release message.

Optionally, before the CU-CP sends the fourth control plane information to the DU, the CU-CP may send fifth control plane information to the DU, where the fifth control plane information is used to indicate a condition that the terminal device enters the inactive state, so that the DU may determine whether the terminal device needs to enter the inactive state according to the fifth control plane information, and report the corresponding condition to the CU-CP. Illustratively, the fifth control plane information may be a UE Context Setup Request, which includes an Inactivity Monitoring Request.

802. The DU receives fourth control plane information from the CU-CP.

The DU may release air interface resources of the terminal device according to the fourth control plane information. For example, after receiving the fourth control plane information, the DU may send an RRC Release message to the UE to Release the relevant air interface resources. And, the DU keeps the connection between the DU and the core network user plane network element and the context of the terminal device, i.e. the connection between the DU and the core network user plane network element is not disconnected and the context of the terminal device is not deleted. Optionally, the DU may also feed back the execution status of RRC Release to the CU-CP, for example, an indication (Indicator) may report whether the execution of RRC Release is successful.

Optionally, before the DU receives the fourth control plane information from the CU-CP, fifth control plane information from the CU-CP may be received, where the fifth control plane information is used to indicate a condition that the terminal device enters the inactive state, that is, the CU-CP may notify the DU of what condition (situation) the terminal device enters the inactive state, so that the DU detects a downlink data transmission state of the terminal device to determine whether the terminal device meets the condition of entering the inactive state. For example, the CU-CP may send a UE Context Request to the DU, where the UE Context Request may be used to configure a UE Context, and the UE Context Request may carry an Inactivity Monitoring Request, which is used by the DU to trigger an RRC Inactivity, that is, to determine whether the terminal device has a condition to enter the Inactive state, or to determine whether the terminal device needs to enter the Inactive state.

After receiving the fifth control plane information, the DU may send feedback information of the fifth control plane information to the CU-CP, where the feedback information is used to feed back whether the CU-CP supports Inactivity Monitoring. If the DU supports Inactivity Monitoring, the DU may send sixth control plane information to the CU-CP, where the sixth control plane information is used to indicate whether the terminal device satisfies the condition of entering the inactive state. For example, the sixth control plane information may include information related to the UE entering the inactive state (e.g., the UE has no downlink data for a long time, and the UE may be considered to have a need to enter the inactive state). Illustratively, the sixth control plane information may be UE inactivity notification. The CU-CP may determine that the terminal device satisfies the condition for entering the inactive state or does not satisfy the condition for entering the inactive state according to the sixth control plane information. If the terminal device meets the condition of entering the inactive state, the CU-CP determines to enable the UE to enter the inactive state, which may be to change the state of the UE from the connected state to the inactive state, that is, to execute step 801.

The above steps 801-802 illustrate how to bring the UE into an inactive state in a CU-UPF convergence scenario. After the UE enters the inactive state, since the DU maintains the connection with the CU-UPF, the DU may receive a data packet of the terminal device from the CU-UPF and needs to perform corresponding processing, that is, this embodiment may further include steps 803 to 811.

It should be noted that steps 801 to 802 and subsequent steps 803 to 811 may be independent from each other, that is, the terminal device may be enabled to enter the inactive state through steps 801 to 802, or may be enabled to enter the inactive state through other manners, which is not limited in this application.

803. The CU-UPF sends the first downlink packet of the terminal device to the DU.

And the packet header of the first downlink data packet carries first QFI information. The first QFI may be used to identify a 5G QoS flow corresponding to the first downlink packet. Wherein, 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 is subjected to the same forwarding processing (e.g., scheduling policy, queue management policy, rate shaping policy, RLC configuration, etc.).

804. The DU receives a first downlink packet of the terminal device from the CU-UPF.

After the DU receives the first downlink data packet, if it is determined that the terminal device is in the inactive state, step 805 may be performed.

805. And when the terminal equipment is in an inactive state, the DU sends user plane information to the CU-UPF.

The reason why the terminal device is in the inactive state, that is, the RRC connection between the DU and the terminal device is disconnected, and the DU cannot issue the data packet to the terminal device, is that 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 a function of buffering packets, and therefore the CU-UPF can buffer the first downlink packet and the second downlink packet.

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 a QoS flow (5G QoS flow) corresponding to the first QFI. The second packet may include all or part of the packets of the QoS flow corresponding to the first QFI except the first packet.

The user plane information may be carried in a PDU, for example, a Downlink Data Delivery Status (DDDS) PDU. Alternatively, the user plane information may be carried in the header of the data packet.

Among them, DDDS PDU is control PDU sent by user plane through F1-U interface to CU-UP. The control PDU is used to report the transmission status of the PDCP PDU (including the PDCP Sequence Number (SN) number and packet loss condition) for flow control. The DDDS PDU can be used to indicate CU-UP on the user plane, this message (carrying the message of the DDDS PDU) is the last DL Status Report, and no uplink or downlink data is subsequently transmitted from this channel (the communication channel for transmitting the DDDS PDU). Alternatively, a DDDS PDU may be used to indicate that the message is an Initial DL DATA DELIVERY STATUS so that a CU-UP can begin sending downstream packets to the DU. Illustratively, the structure of the DDDS PDU may be as shown in table 1.

TABLE 1

It should be noted that, an extension bit may be added on the basis of the DDDS PDU shown in table 1, and the extension bit carries the user plane information, 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.

806. The CU-UPF receives user plane information from the DU.

And the CU-UPF can stop sending the second downlink data packet corresponding to the terminal equipment according to the user plane information and cache the first downlink data packet and the second downlink data packet.

807. The DU transmits the second control plane information to the CU-CP.

The second control plane information comprises first QFI information and first PPI information, and the first QFI information and the first PPI information are used for determining a paging strategy of the terminal device. Optionally, the second control plane information may further include a gNB-CU-CP UE F1AP ID and a gNB-DU UE F1AP ID for identifying the terminal device. For example, the second control plane information may be carried in DL Data Notification.

808. The CU-CP receives second control plane information from the DU.

The CU-CP queries a 5G QoS Identifier (5G QoS Identifier, 5QI) and an Allocation and Retention Priority (ARP) according to the first QFI information. The 5QI is used to determine QoS parameters of QoS Flow, such as delay, packet error rate, and the like, and the ARP is used to determine priorities between different QoS flows. The CU-CP determines a Paging strategy according to the first PPI information, after the Paging strategy is determined, the Paging message can be started to be sent to the DU within the control range of the CU-CP, and the DU which receives the Paging message can initiate Paging by the UE within the coverage range of the DU.

It should be noted that there is no necessary execution sequence between steps 807 to 808 and steps 805 to 806, and steps 805 to 806 may be executed first, and then steps 807 to 808 are executed; or step 807 to step 808 may be performed first, and step 805 to step 806 may be performed later; step 805 to step 806 and step 807 to step 808 may also be performed simultaneously, which is not specifically limited in this embodiment.

After step 807 to step 808, if the CU-UPF continues to issue a data packet corresponding to the second QFI to the DU, the embodiment of the present application may further include step 809 to step 811.

809. And the DU receives a third downlink data packet corresponding to the terminal equipment from the CU-UPF.

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.

810. The DU transmits third control plane information to the CU-CP.

The third control plane information comprises second QFI information and second PPI information, and the second QFI information and the second PPI information are used for determining the paging strategy of the terminal device. For example, the third control plane information may be carried in a new DL Data Notification message, which is different from the DL Data Notification message carrying the second control plane information.

811. The CU-CP receives third control plane information from the DU.

The CU-CP can determine the Paging strategy again according to second PPI information in the third control plane information, and 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 policy determined according to the first PPI information is not lower than (higher than or equal to) the priority of the Paging policy determined according to the second PPI information, the CU-CP may still perform Paging on the terminal device according to the Paging policy determined by the first PPI information.

Step 803-step 811 describe how Paging is triggered (i.e. Paging is done for the terminal device) in the CU-UPF association scenario. After triggering paging, the DU may receive an RRC recovery request from the terminal device, and the DU may request the CU-CP to recover the RRC connection of the terminal device, that is, this embodiment of the present application may further include steps 812 to 818.

It should be noted that, step 803 to step 811 and step 812 to step 818 may be independent from each other, that is, the paging may be triggered through step 803 to step 811, or may be triggered through other manners, which is not limited in this application.

812. The DU receives an RRC recovery Request (RRC Resume Request) from the terminal device.

The terminal device is the terminal device that receives the paging message.

813. The DU transmits an Initial uplink RRC Message (Initial UL RRC Message Transfer) to the CU-CP.

The initial uplink RRC message is used to request recovery of RRC connection of the terminal device.

814. The CU-CP sends first control plane information to the DU, the first control plane information being used to resume the RRC connection of the terminal device.

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 id of the CU-UPF, so that the DU may request the CU-UPF for the data of the terminal device according to the uplink port id of the CU-UPF. The upstream port identifier of the CU-UPF may be, for example, a F1-U UL 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 id 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 id of the CU-UPF, and the data of the terminal device may be that the Last Serving DU indicates the CU-UPF to cache. For example, the first control plane information may be carried in a UE Context Setup Request.

Meanwhile, the CU-CP can perform RRC Resume signaling interaction with the UE to enable the UE to be converted from an inactive state to a connected state.

In addition, if the DU is not the last DU connected before the terminal device enters the inactive state, the CU-CP may send a terminal device context release message to the last DU connected before the terminal device enters the inactive state, where 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 the DU switch occurs, the CU-CP may send a UE Context Release message to the Last Serving DU, instructing the DU to Release the connection with the CU-UPF and the UE Context, thereby saving communication resources.

815. The DU receives first control plane information from the CU-CP.

If the DU is the last DU connected before the terminal device enters the inactive state, the DU may perform step 816, and if the DU is not the last DU connected before the terminal device enters the inactive state, the DU may perform step 818.

816. And if the DU is the last DU connected before the terminal equipment enters the non-activated state, the DU sends first indication information to the CU-UPF, and the first indication information enables a data packet corresponding to the terminal equipment to be sent to the DU.

That is, if the DU does not have DU handover, the DU sends first indication information to the CU-UPF, and the first indication information 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. Illustratively, the first indication information may be carried in the DDDS PDU.

817. The CU-UPF receives the first indication information from the DU.

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

Alternatively, CU-UPF may report the F1-U port change of DU to AMF/SMF.

818. And if the DU is not the last DU connected before the terminal equipment enters the non-activated state, the DU sends second indication information to the CU-UPF, the second indication information enables the CU-UPF and the DU to be established with downlink connection, and a data packet of the terminal equipment is sent to the DU.

That is, if the DU is switched, the DU sends second indication information to the CU-UPF, and the second indication information enables the CU-UPF to establish downlink connection with the DU and sends a data packet of the terminal device (cached in the Last Serving DU indication) to the DU. The second indication information may be carried in the DDDS PDU.

819. The CU-UPF receives second indication information from the DU.

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

Alternatively, CU-UPF may report the F1-U port change of DU to AMF/SMF.

In the embodiments provided by the present application, the method provided by the embodiments of the present application is introduced from the perspective of the DU, the CU-CP, the CU-UPF, and the interaction between the DU, the CU-CP and the CU-UPF, respectively. In order to implement the functions in the method provided by the embodiments of the present application, the DU, the CU-CP, and the CU-UPF may include a hardware structure and/or a software module, and the functions are implemented in the form of a hardware structure, a software module, or a hardware structure and a software module. Whether any of the above-described functions is implemented as a hardware structure, a software module, or a hardware structure plus a software module depends upon the particular application and design constraints imposed on the technical solution.

In the case of dividing the functional modules by corresponding functions, fig. 9 shows a schematic diagram of a possible structure of DU9 involved in the foregoing embodiment, where DU9 includes: a receiving unit 901 and a transmitting unit 902. In this embodiment, the receiving unit 901 is configured to receive first control plane information from the centralized unit-control plane CU-CP, where the first control plane information is used to instruct to resume radio resource control RRC connection of the terminal device; a sending unit 902, configured to send first indication information to a centralized unit-user plane function network element CU-UPF, where the first indication information enables a data packet corresponding to a terminal device to be sent to a DU; or the sending unit 902 is configured to send second indication information to the CU-UPF, where the second indication information enables establishment of a downlink connection between the CU-UPF and the DU, and a data packet of the terminal device is sent to the DU.

In the embodiment of the method shown in fig. 8, the receiving unit 901 is configured to support the DU to perform the processes 802, 804, 809, 812 and 815 in fig. 8. The sending unit 902 is configured to support the DU to perform the processes 805, 807, 810, 813 and 816 in fig. 8. All relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again.

The receiving unit 901 or the sending unit 902 may be the communication interface 704 in fig. 7.

In the case of dividing the functional modules by corresponding functions, fig. 10 shows a schematic diagram of a possible structure of the CU-CP10 involved in the above embodiment, where the CU-CP10 includes: a transmission unit 1001. In this embodiment of the present application, the sending unit 1001 is configured to send first control plane information to the distributed unit DU, where the first control plane information is used to recover radio resource control RRC connection of the terminal device; if the DU is the last DU connected before the terminal equipment enters the inactive state, the first control plane information comprises an uplink port identifier of a centralized unit-user plane function network element CU-UPF; and if the DU is not the last DU connected before the terminal equipment enters the inactive state, the first control plane information comprises the uplink port identification of the CU-UPF and the downlink port information of the last DU serving the terminal equipment.

In the method embodiment shown in fig. 8, sending unit 1001 is configured to support the CU-CP to perform processes 801 and 814 in fig. 8. Optionally, the CU-UPF may further include a receiving unit 1002 for supporting the CU-CP to perform processes 808 and 811 in fig. 8. All relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again.

The transmitting unit 1001 or the receiving unit 1002 may be the communication interface 704 in fig. 7.

In the case of dividing the function modules by corresponding functions, fig. 11 shows a schematic diagram of a possible structure of the CU-UPF11 involved in the above embodiment, and the CU-UPF11 includes: a receiving unit 1101. In this embodiment of the present application, the receiving unit 1101 is configured to receive first indication information from a distributed unit DU, where the DU is a last DU connected before a terminal device enters an inactive state, and a data packet corresponding to the first indication information enabling the terminal device is sent to the DU; or the receiving unit 1101 is configured to receive second indication information from a DU, where the DU is not the last DU connected before the terminal device enters the inactive state, the second indication information enables establishment of a downlink connection between the CU-UPF and the DU, and a data packet of the terminal device is sent to the DU.

In the method embodiment shown in FIG. 8, the receiving unit 1101 is configured to support the CU-UPF to perform the processes 806 and 817 in FIG. 8. Optionally, the CU-UPF may further include a sending unit 1102 for supporting the CU-UPF to perform the process 803 in fig. 8. All relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again.

The receiving unit 1101 or the sending unit 1102 may be the communication interface 704 in fig. 7.

For example, the DU, CU-CP and CU-UPF in the respective device embodiments and the DU, CU-CP and CU-UPF in the method embodiments may correspond completely, and the corresponding steps may be performed by corresponding modules or units, for example, the communication module (transceiver) may perform the steps of transmitting and/or receiving in the method embodiments, and other steps besides transmitting and receiving may be performed by the processing unit (processor). The functions of the specific elements may be referred to in the respective method embodiments. The transmitting unit and the receiving unit can form a transceiving unit, and the transmitter and the receiver can form a transceiver to realize transceiving function together; the processor may be one or more.

Illustratively, the functions of the DU, CU-CP and CU-UPF may be implemented by a chip, the processing unit may be implemented by hardware, or may be implemented by software, and when implemented by hardware, the processing unit may be a logic circuit, an integrated circuit, or the like; when implemented in software, the processing unit may be a general-purpose processor implemented by reading software code stored in a memory unit, which may be integrated in the processor or located external to the processor.

The respective device embodiments described above wherein the DU, CU-CP and CU-UPF correspond exactly to the DU, CU-CP and CU-UPF in the method embodiments, the respective steps are performed by respective modules or units, e.g. the sending module (transmitter) method performs the steps sent in the method embodiments, the receiving module (receiver) performs the steps received in the method embodiments, and the other steps than sending and receiving may be performed by the processing module (processor). The functionality of the specific modules may be referred to in the respective method embodiments. The transmitting module and the receiving module can form a transceiving module, and the transmitter and the receiver can form a transceiver to realize transceiving function together; the processor may be one or more.

The division of the modules or units in the embodiments of the present application is schematic, and only one logical function division is provided, and in actual implementation, there may be another division manner, and in addition, each functional module in each embodiment of the present application may be integrated in one processor, may also exist alone physically, or may also be integrated in one module by two or more modules. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. For example, in the embodiment of the present application, the receiving unit and the transmitting unit may be integrated into the transceiving unit.

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

It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present application without departing from the scope of the application. Thus, if such 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 encompass such modifications and variations.

Claims

1. A communication method applied to a centralized unit CU-distributed unit DU architecture in the DU, the method comprising:

the DU receives first control plane information from a centralized unit-control plane CU-CP, the first control plane information being used to instruct recovery of a radio resource control, RRC, connection of the terminal device;

if the DU is the last DU connected before the terminal equipment enters the non-activated state, the DU sends first indication information to a centralized unit-user plane function network element CU-UPF, and the first indication information enables a data packet corresponding to the terminal equipment to be sent to the DU;

and if the DU is not the last DU connected before the terminal equipment enters the non-activated state, the DU sends second indication information to the CU-UPF, the second indication information enables the CU-UPF to establish downlink connection with the DU, and a data packet of the terminal equipment is sent to the DU.

2. The method according to claim 1, wherein before the distributed unit DU receives the first control plane information from the centralized unit-control plane CU-CP, the method further comprises:

the DU receives an RRC recovery request from the terminal equipment;

and the DU sends an initial uplink RRC message to the CU-CP, wherein the initial uplink RRC message is used for requesting to recover the RRC connection of the terminal equipment.

3. The method according to claim 1 or 2, wherein before the distributed unit DU receives the first control plane information from the centralized unit-control plane CU-CP, the method further comprises:

the DU receives a first downlink data packet of a terminal device from the CU-UPF, wherein the packet header of the first downlink data packet comprises first QFI (quality of service) flow identification QFI (quality of service) information, and the first QFI information is used for identifying a QoS (quality of service) flow of the first downlink data packet;

and when the terminal equipment is in an inactive state, the DU sends user plane information to the CU-UPF, wherein the user plane information is used for indicating the CU-UPF to stop sending a second downlink data packet corresponding to the terminal equipment, the packet header of the second downlink data packet comprises the first QFI information, and the user plane information is also used for indicating the CU-UPF to cache the first downlink data packet and the second downlink data packet.

4. The method of claim 3, further comprising:

and the DU sends second control plane information to the CU-CP, wherein the second control plane information comprises the first QFI information and first paging strategy identification PPI information, and the first QFI information and the first PPI information are used for determining the paging strategy of the terminal equipment.

5. The method of claim 4, further comprising:

the DU receives a third downlink data packet corresponding to the terminal device from the CU-UPF, wherein a packet header of the third downlink data packet comprises 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, wherein the third control plane information comprises the second QFI information and the second PPI information, and the second QFI information and the second PPI information are used for determining a paging strategy of the terminal device.

6. The method according to any one of claims 1-5, further comprising:

the DU receives fourth control plane information from the CU-CP, wherein the fourth control plane information is used for indicating the DU to release air interface resources of terminal equipment, and reserving the connection between the DU and a centralized unit-user plane function network element CU-UPF and the context of the terminal equipment;

and the DU releases the air interface resource of the terminal equipment.

7. The method of claim 6, wherein before the DU receives fourth control plane information from the CU-CP, the method further comprises:

the DU receives fifth control plane information from the CU-CP, wherein the fifth control plane information is used for indicating the condition that the terminal equipment enters an inactive state;

and the DU sends sixth control plane information to the CU-CP, wherein the sixth control plane information is used for indicating whether the terminal equipment meets the condition of entering an inactive state.

8. A communication method 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 a distributed unit DU, wherein the first control plane information is used for recovering Radio Resource Control (RRC) connection of terminal equipment;

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 functional 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 an uplink port identifier of the CU-UPF and downlink port information of the last DU serving the terminal device.

9. The method of claim 8, wherein if the DU is not a last DU connected before the terminal device enters the inactive state, the method further comprises:

and the CU-CP sends a terminal device context release message to the last DU connected before the terminal device enters the inactive state, wherein the terminal device context release message is used for indicating 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:

and the CU-CP receives second control plane information from the DU, wherein the second control plane information comprises first QFI (quality of service) flow identification (QFI) information and first paging strategy identification (PPI) information, and the first QFI information and the first PPI information are used for the CU-CP to determine a paging strategy for the terminal equipment.

11. The method of claim 10, further comprising:

the CU-CP receiving 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 being used for the CU-CP to determine a paging strategy for the terminal device, the second QFI information being different from the first QFI information.

12. The method according to any one of claims 8-11, further comprising:

and the CU-CP sends fourth control plane information to the DU, wherein the fourth control plane information is used for indicating the DU to release air interface resources of the terminal equipment, and reserving the connection between the DU and a core network user plane network element and the context of the terminal equipment.

13. The method of claim 12, wherein before the CU-CP sends fourth control plane information to the DU, the method further comprises:

the CU-CP sends fifth control plane information to the DU, wherein the fifth control plane information is used for indicating the condition that the terminal equipment enters an inactive state;

the CU-CP receiving sixth control plane information from the DU, the sixth control plane information indicating whether the terminal device satisfies a condition for entering an inactive state.

14. A method of communication, comprising:

a centralized unit-user plane function network element CU-UPF receives first indication information from a distributed unit DU, wherein the DU is the last DU connected before a 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 second indication information from the DU, the DU is not the last DU connected before the terminal equipment enters the non-activated state, the second indication information enables the CU-UPF to establish downlink connection with the DU, and a data packet of the terminal equipment is sent to the DU.

15. The method of claim 14, further comprising:

the CU-UPF sends a first downlink data packet to the DU, and the packet header of the first downlink data packet carries first service quality flow identification QFI information;

the CU-UPF receives user plane information from the DU, wherein the user plane information is used for indicating the CU-UPF to stop sending a second downlink data packet corresponding to the terminal equipment, a packet header of the second downlink data packet comprises the first QFI information, and the user plane information is also used for indicating the CU-UPF to cache the first downlink data packet and the second downlink data packet;

and the CU-UPF stops sending the second downlink data packet and caches the first downlink data packet and the second downlink data packet.

16. A communications device, the communications device being a centralized unit, CU, distributed unit, DU, architecture in the DU, comprising:

a receiving unit, configured to receive first control plane information from a centralized unit-control plane CU-CP, the first control plane information being used to instruct a radio resource control, RRC, connection of a recovery terminal device;

a sending unit, configured to send first indication information to a centralized unit-user plane function network element CU-UPF, where the first indication information enables a data packet corresponding to the terminal device to be sent to the DU; or

The sending unit is configured to send second indication information to the CU-UPF, where the second indication information enables establishment of a downlink connection between the CU-UPF and the DU, and a data packet of the terminal device is sent to the DU.

17. The communications apparatus of claim 16, wherein the receiving unit is further configured to:

receiving an RRC recovery request from the terminal device;

the sending unit is further configured to send an initial uplink RRC message to the CU-CP, where the initial uplink RRC message is used to request to recover the RRC connection of the terminal device.

18. The communication apparatus according to claim 16 or 17, wherein the receiving unit is further configured to:

receiving a first downlink data packet of a terminal device from the CU-UPF, wherein the packet header of the first downlink data packet comprises first QFI (quality of service flow identification) QFI (QFI information), and the first QFI information is used for identifying the QoS (quality of service) flow of the first downlink data packet;

when the terminal device is in an inactive state, the sending unit is further configured to send user plane information to the CU-UPF, 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, a packet 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 communications apparatus as claimed in claim 18, wherein the sending unit is further configured to:

sending second control plane information to the CU-CP, wherein the second control plane information comprises the first QFI information and first paging strategy identification PPI information, and the first QFI information and the first PPI information are used for determining a paging strategy of the terminal device.

20. The communications apparatus of claim 19, wherein the receiving unit is further configured to:

receiving a third downlink data packet corresponding to the terminal device from the CU-UPF, wherein a packet header of the third downlink data packet comprises second QFI information and second PPI information, and the second QFI information is different from the first QFI information;

the sending unit is further configured 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 for determining a paging policy of the terminal device.

21. The communication device according to any of claims 16-20, wherein the receiving unit is further configured to:

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 reserve a connection between the DU and a centralized unit-user plane functional network element CU-UPF and a context of the terminal device through a storage unit;

and the processing unit is used for releasing the air interface resource of the terminal equipment.

22. The communications apparatus of claim 21, wherein the receiving unit is further configured to:

receiving fifth control plane information from the CU-CP, wherein the fifth control plane information is used for indicating a condition that the terminal equipment enters an inactive state;

the sending unit is further configured 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 a condition of entering an inactive state.

23. A communication apparatus, the communication apparatus being a centralized unit-control plane CU-CP in a centralized unit CU-distributed unit DU architecture, comprising:

a sending unit, configured to send first control plane information to a distributed unit DU, where the first control plane information is used to recover radio resource control RRC connection of a terminal device;

24. The communications apparatus as claimed in claim 23, wherein if the DU is not the last DU connected before the terminal device enters the inactive state, the sending unit is further configured to:

and sending a terminal device context release message to the last DU connected before the terminal device enters the inactive state, wherein the terminal device context release message is used for indicating 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 apparatus according to claim 23 or 24, further comprising a receiving unit configured to:

and receiving second control plane information from the DU, wherein the second control plane information comprises first quality of service flow identification (QFI) information and first paging strategy identification (PPI) information, and the first QFI information and the first PPI information are used for the CU-CP to determine a paging strategy for the terminal equipment.

26. The communications apparatus of claim 25, wherein the receiving unit is further configured to:

receiving 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 being used by the CU-CP to determine a paging policy for the terminal device, the second QFI information being different from the first QFI information.

27. The communication device according to any of claims 23-26, wherein the sending unit is further configured to:

28. The communications apparatus of claim 27, wherein the sending unit is further configured to:

sending fifth control plane information to the DU, where the fifth control plane information is used to indicate a condition that the terminal device enters an inactive state;

a receiving unit, further configured to receive sixth control plane information from the DU, where the sixth control plane information is used to indicate whether the terminal device satisfies a condition of entering an inactive state.

29. A communication device, said communication device being a centralized unit-user plane function network element, CU-UPF, comprising:

a receiving unit, configured to receive first indication information from a distributed unit DU, where the DU is a last DU connected before a 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, configured to receive second indication information from a DU, where the DU is not a last DU connected before a terminal device enters an inactive state, the second indication information enables establishment of a downlink connection between the CU-UPF and the DU, and a data packet of the terminal device is sent to the DU.

30. The apparatus according to claim 29, further comprising a transmitting unit configured to:

sending a first downlink data packet to the DU, wherein a packet header of the first downlink data packet carries first service quality flow identification QFI information;

the receiving unit is configured to receive 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, a packet 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 sending unit is used for stopping sending the second downlink data packet and caching the first downlink data packet and the second downlink data packet through the caching unit.

31. A communication device, comprising a transceiver, a memory, and a processor, the processor and the memory coupled;

the memory is for storing computer-executable instructions that, when executed by the communication device, are executed by the processor to cause the communication device to perform the method of any of claims 1-7 or claims 8-13 or claims 14-15.

32. A computer-readable storage medium comprising instructions which, when executed on a computer, cause the computer to perform the method of any of claims 1-7 or claims 8-13 or claims 14-15.

33. A communication system, the communication system comprising: the communication device of any one of claims 16-22, the communication device of any one of claims 23-28, and the communication device of any one of claims 29-30.