WO2021244191A1

WO2021244191A1 - Method and device for implementing mutual switching between 4g and 5g networks and storage medium

Info

Publication number: WO2021244191A1
Application number: PCT/CN2021/090385
Authority: WO
Inventors: 程岳
Original assignee: 大唐移动通信设备有限公司
Priority date: 2020-06-03
Filing date: 2021-04-28
Publication date: 2021-12-09
Also published as: MX2022006765A; CN113766580A; CN113766580B

Abstract

Provided in the embodiments of the present disclosure are a method and device for implementing mutual switching between 4G and 5G networks and a storage medium. The method comprises: in a switching preparation stage, a source base station establishing a forwarding channel; in a switching execution stage, sending a switching command to a UE, carrying out protocol header stripping processing on a PDU in a sent queue of a PDCP layer to form downlink forwarding data, and forwarding the downlink forwarding data to a target base station by means of the forwarding channel, so that the target base station can carry out duplication removal processing on the downlink forwarding data according to a receiving feedback of a TCP layer and then send the downlink forwarding data to the UE; and forwarding downlink data from a core network to the target base station by means of the forwarding channel. According to the present disclosure, protocol header stripping processing is carried out on a message processed by protocol on the source side in the switching execution stage to form an original IP message, the original IP message is transmitted to the target base station by means of a forwarding link, and the repeated sending of the message on the TCP layer of the target side is reduced, thereby achieving lossless forwarding during network switching, and ensuring the stability of the transmission rate.

Description

Method, device and storage medium for implementing mutual switching between 4G and 5G networks

Cross-references to related applications

This disclosure requires the priority of the Chinese patent publication filed on June 3, 2020 with the publication number 2020104947881 and the publication title "Methods, Devices and Storage Media for Inter-switching 4G and 5G Networks", which are incorporated by reference in their entirety. Into this article.

Technical field

The present disclosure relates to the field of communication technology, and more specifically, to a method, device, and storage medium for implementing mutual switching between 4G and 5G networks.

Background technique

5G (5th-Generation, fifth-generation mobile communication system)-NR (New Radio, new wireless technology) Due to the high frequency spectrum, it can only be covered by hotspots for a long time. Therefore, 5G and 4G (4th-Generation, fourth (Generation mobile communication system) network switching will exist for a long time.

Due to the PDCP (Packet Data Convergence Protocol) SN (Sequence number) length may be different under the two networks, and there is no message of the SN transmission status, therefore, when 4G and 5G are interoperated and switched , Using FullConfig (full configuration), that is, when the handover occurs, the PDCP on the target side is rebuilt, and the PDCP SNs on both sides are no longer continuous (that is, the target side cannot learn the packet sending status of the source side), so 4G and 5G are mutually When switching, lossless switching is no longer supported. When switching from 5G to 4G, only the downlink data packets are forwarded and lossless switching is not supported. When switching from 4G to 5G, the PDCP SDU (Service Data Unit) assigned to the SN is not forwarded. When the two systems are switched to each other , Only forward the new downlink data packets received from the core network during the handover process. That is, the current 4G and 5G handover does not support lossless handover. During the handover, the downlink data that has been processed by the source base station cannot be forwarded to the target base station. The continuity in turn triggers retransmissions at the TCP layer of the target network, resulting in a steep drop in the target base station rate and poor user experience.

For example: UE (terminal equipment) accesses 4G and receives packets a1 a2 a3 a4 a5 a6 a7, where the serial number is PDCP SN. Assuming that packets a1 a2 a3 have been sent to the UE, a4 a5 a6 a7 add PDCP SN post-processing and send it to RLC (Radio Link Control, radio link layer control protocol) for MAC (Medium Access Control, media access control) scheduling. At this time, the handover occurs, and the UE uplink confirms the receipt of a1, the UE receives a2 but does not confirm, and does not receive a3. At this time, it continues to receive bc d e packets from the core network. As the handover occurs, 4G forwards b c d e packets to 5G. After the UE switches to 5G, due to the PDCP layer reconstruction, the access network layer cannot report that a2 has received and a3 has not received it. The 5G base station continues to send b0 c1 d2 e3. At this time, packets a3 a4 a5 a6 a7 These packets that have not been successfully delivered on the source side air interface and that have not been delivered on the air interface are discarded, which triggers the retransmission of packets a3 to a7 at the TCP layer of the target network, thus causing the TCP layer to enter the slow start phase , Causing a steep drop in speed.

Summary of the invention

The embodiments of the present disclosure provide a method, device, and storage medium for implementing 4G and 5G network inter-switching that overcomes the above problems or at least partially solves the above problems.

In the first aspect, embodiments of the present disclosure provide a method for implementing mutual handover between 4G and 5G networks, including:

In the handover preparation phase, the source base station establishes the forwarding channel;

In the handover execution stage, the source base station sends a handover command to the user terminal UE, strips off the protocol header of the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol, and forms the downlink forward data. The forwarded data is forwarded to the target base station through the forwarding channel, so that the target base station performs repetition processing on the downlink forwarded data according to the received feedback of the TCP layer of the transmission control protocol and then sends it to the UE;

The downlink data from the core network is forwarded to the target base station through the forwarding channel, and the forwarding is terminated after receiving the message indicating the completion of data transmission sent by the core network, so that the target base station can transfer the data from the target base station. The downlink data of the core network is sent to the UE.

Optionally, the PDUs in the sent queue of the PDCP layer specifically include: PDUs to be sent to the UE to which the PDCP sequence number SN has been added and PDUs to be sent to the UE to be confirmed.

Optionally, the process of stripping off the protocol header on the PDUs in the sent queue of the PDCP layer is specifically:

If the UE is in a 4G network, the PDCP SN accumulated in the PDCP layer with PDCP SN added is stripped according to the position order of the PDU, where the position order of the PDU is determined according to the size of the SN and 4G PDCP SN; or,

If the UE is in a 5G network, the PDCP SN accumulated in the PDCP layer is added to the PDCP layer, according to the position order of the PDU, first strip off the PDCP SN, and then strip off the service data adaptation protocol SDAP protocol header, where the position of the PDU The order is determined according to the size of SN and 5G PDCP SN.

In the second aspect, the embodiments of the present disclosure provide a method for implementing mutual handover between 4G and 5G networks, including:

When the target base station receives the handover complete message sent by the user terminal UE, it sends the downlink forwarding data received through the forwarding channel to the UE, and schedules the uplink data. If the uplink data is received, it is received according to the TCP layer of the transmission control protocol. Feedback to perform deduplication processing on the downlink forward data, and send the downlink forward data after deduplication processing to the UE;

Sending the downlink data from the core network to the UE after the transmission of the downlink forwarding data is completed;

Wherein, the downlink forwarding data is obtained after the source base station strips off the protocol header of the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol.

Optionally, the performing repetition processing on the downlink forward data according to the received feedback of the TCP layer specifically includes:

For the received multiple uplink TCP feedback packets, analyze the multiple uplink TCP feedback packets to obtain the message sequence number and the feedback sequence number of the TCP feedback packet corresponding to each thread identifier;

For each thread ID, parse the downlink data packet to be sent corresponding to the current thread ID, and obtain the message sequence number and the feedback sequence number of the downlink data packet;

According to the message sequence number and feedback sequence number of the TCP feedback packet corresponding to the current thread identifier, and the message sequence number and feedback sequence number of the downlink data packet, it is judged whether the pre-defined deduplication processing condition is satisfied, and if it is satisfied, all the messages are deleted. Describe the downlink data packet.

Optionally, it also includes:

If the uplink data is not received, all the downlink forward data received through the forward channel are sent to the UE.

In the third aspect, embodiments of the present disclosure provide a device for implementing mutual handover between 4G and 5G networks, including:

The forwarding channel establishment module is used to establish the forwarding channel during the handover preparation phase;

The first forwarding module is used to send a handover command to the user terminal UE during the handover execution phase to strip the protocol header of the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol to form downlink forward data , Forwarding the downlink forwarding data to the target base station through the forwarding channel, so that the target base station performs repetition processing on the downlink forwarding data according to the received feedback of the TCP layer of the transmission control protocol and then sends it to the UE ；

The second forwarding module is used to forward the downlink data from the core network to the target base station through the forwarding channel, until it terminates the forwarding after receiving a message indicating the completion of data transmission sent by the core network for The target base station sends the downlink data from the core network to the UE.

Optionally, the first forwarding module is specifically configured to:

In a fourth aspect, embodiments of the present disclosure provide a device for implementing mutual handover between 4G and 5G networks, including:

The deduplication processing module is used to send the downlink forwarding data received through the forwarding channel to the UE when the handover complete message sent by the user terminal UE is received, and to schedule the uplink data, if the uplink data is received, according to the transmission control The received feedback of the protocol TCP layer performs deduplication processing on the downlink forward data, and sends the downlink forward data after deduplication processing to the UE;

A data sending module, configured to send downlink data from the core network to the UE after the downlink forwarding data has been sent;

Optionally, the weight removal processing module is specifically configured to:

Optionally, it also includes:

The second sending module is configured to send all the downlink forward data received through the forward channel to the UE if the uplink data is not received.

In a fifth aspect, embodiments of the present disclosure provide a network-side device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor. The steps of the method for implementing mutual handover between 4G and 5G networks described in the aspect or the second aspect.

In a sixth aspect, embodiments of the present disclosure provide a non-transitory computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the 4G and 5G as provided in the first or second aspect are implemented. Steps of the implementation method of network switching.

The implementation method, device, and storage medium for switching between 4G and 5G networks provided by the embodiments of the present disclosure perform reverse protocol processing on packets that have been protocol-processed on the source side during the switching execution phase, stripping off the PDCP PDU two-layer protocol header , Forming the original IP message, passing it through the forwarding link to the target base station for priority transmission, and on the target base station side at the TCP level to minimize the repeated transmission of the message on the air interface, which can realize lossless forwarding when switching data, thereby ensuring transmission The stability of the rate.

Description of the drawings

In order to explain the embodiments of the present disclosure or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description These are some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

Figure 1 is a schematic diagram of a 5G and 4G interoperable network structure in the prior art;

Figure 2 is a schematic diagram of the processing flow of the L2 data stream protocol in the existing 5G NR;

3 is a schematic flowchart of a method for implementing mutual handover between 4G and 5G networks provided by an embodiment of the disclosure;

4 is a schematic diagram of protocol header processing provided by an embodiment of the disclosure;

5 is a schematic flowchart of a method for implementing mutual handover between 4G and 5G networks provided by an embodiment of the disclosure;

Fig. 6 is a schematic structural diagram of a device for implementing mutual handover between 4G and 5G networks provided by an embodiment of the disclosure;

FIG. 7 is a schematic structural diagram of a device for implementing mutual handover between 4G and 5G networks provided by an embodiment of the disclosure;

FIG. 8 is a schematic structural diagram of a network side device provided by an embodiment of the disclosure.

detailed description

In order to make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments These are a part of the embodiments of the present disclosure, but not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative work shall fall within the protection scope of the present disclosure.

Before describing in detail the implementation method, device, and storage medium for switching between 4G and 5G networks provided by the embodiments of the present disclosure, first, the technical background of the present disclosure will be introduced.

Technical background 1: TCP layer data transmission and confirmation process

Transmission Control Protocol TCP (Transmission Control Protocol) has an important principle: the Sequence number (data sequence number, abbreviated as SEQ) in the TCP format represents the starting sequence number of the data in the current data packet. The feedback sequence number is Acknowledgement number, which represents the response sequence number after receiving a certain data packet from the other party. If a certain data packet sent by the other party is received, an ACK (Acknowledgement) response data packet must be returned to the other party. The acknowledgement number part of the header of the data packet returns SEQ+ according to the SEQ and actual data length of the data sent by the other party. The actual data length +1 means that this data packet has been received and is ready to accept the next packet of data. The sender receives this response and knows that the data packet has been received by the other party after calculating the value. Another important design principle of the TCP protocol is to set a receiving window on the receiving side (the size of the receiving window does not shrink) for sorting out-of-sequence messages and reordering messages that may be retransmitted due to timeouts.

Technical background 2: 5G and 4G interoperability process

A 5G and 4G interoperable network structure is shown in Figure 1, where 4G access network universal terrestrial radio access UTRA (Universal Terrestrial Radio Access) evolved E-UTRAN (Evolved UTRA) and 5G access network NG-RAN (The There is no physical interface between the gNB and the 5G CN Radio Access Network. When a terminal UE switches between the two networks, interoperability can only be achieved through the 4G Evolved Packet Core (EPC) and 5G Between 5GC (5G core) of the core network (N26 interface).

The handover process is basically divided into a handover preparation phase, a handover execution phase, and a handover completion phase. Among them, in the handover preparation phase (before sending the UE to execute the command), a forward link will be established between the 5G access network NR-RAN and the core network 5GC and the 4G access network E-UTRAN and the core network EPC. After sending a handover command (handover execution phase) to the terminal equipment UE (User Equipment), the new downlink data packet received from the core network is forwarded from the source base station to the target base station.

Technical background 3: Data processing in the L2 protocol stack

Figure 2 shows the protocol processing flow of the L2 data stream in 5G NR. In the fifth-generation mobile communication system 5G NR (5th-Generation-New Radio), the SDAP (Service Data Adaptation Protocol, Service Data Adaptation Protocol) protocol maps the QoS stream domain (generally carrying TCP\IP packets) to radio bearer resources On block RB (Resource Block), SDAP protocol header is added to the Internet Protocol IP (Internet Protocol) message. After the PDCP (Packet Data Convergence Protocol) layer receives the service data unit SDU (Service Data Unit) corresponding to a certain quality of service Qos (Quality of Service) in SDAP, it adds the PDCP protocol header and performs optional encryption and After the integrity operation, the RLC SDU is formed and submitted to the RLC. For each SDU, the RLC adds the RLC protocol header to form the RLC PDU. When scheduling, the MAC stores the buffer to be transmitted according to the current authorized terabyte (Terabyte) block size. The multiple RLC PDUs are connected in series. The purpose of this is to enable RLC and PDCP to perform protocol processing in advance, so as to reduce the delay of media access control MAC (Medium Access Control) in the scheduling of protocol processing.

In the 4G Long Term Evolution (Long Term Elution) system, one difference is that there is no SDAP protocol layer, and the other difference is that RLC PDUs are only grouped when MAC scheduling is performed. Therefore, one RLC PDU contains multiple PDCP PDUs. But the same processing is: after the PDCP PDU is sent to the RLC, the PDCP protocol layer buffers the PDU, and if it receives a confirmation that the RLC layer has successfully delivered the PDU, the buffered PDU is deleted. The purpose of buffering is to prevent the source base station from sending the buffered PDCP PDU to the target base station for retransmission when a handover occurs. At this time, the buffered PDCP PDU includes two types: one is sent to the UE but not confirmed to be received , The first category is to be scheduled. The PDCP protocol layer stores these two types of PDUs in its sent queue. The sequence number SN (Sequence number) is used in the PDCP layer for sequential delivery and lossless transmission.

As shown in FIG. 3, a schematic flow chart of the method for implementing mutual handover between 4G and 5G networks provided by an embodiment of the present disclosure, which is applied to a source base station, includes:

Step 100: In the handover preparation phase, the source base station establishes a forwarding channel;

Among them, forwarding means forward, and the source base station establishes a forwarding channel, that is, establishing a forwarding link between the 5G access network NR-RAN and the core network 5GC, and the 4G access network E-UTRAN and the core network EPC.

Step 101: In the handover execution phase, the source base station sends a handover command to the user terminal UE, strips off the protocol header of the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol, and forms the downlink forward data, The downlink forwarding data is forwarded to the target base station through the forwarding channel, so that the target base station performs repetition processing on the downlink forwarding data according to the reception feedback of the TCP layer of the transmission control protocol and then sends it to the UE;

Specifically, in the handover execution phase, the source base station sends a handover command to the user terminal UE. After the UE receives the handover command from the source base station, it will perform a network handover operation. If the UE is currently in a 4G network, it will switch to a 5G network. If you are on a 5G network, switch to a 4G network.

When the UE is in the 4G network, the handover command sent by the source base station to the UE is specifically the HO From E-UTRAN Command message; when the UE is in the 5G network, the handover command sent by the source base station to the UE is the HO Command message.

After the source base station sends a handover command to the user terminal UE, the packet that has been processed by the source base station by agreement when the handover occurs is stripped off the protocol header and then forwarded to the target base station.

Specifically, the message that has been processed by the protocol at the source base station refers to the PDU in the sent queue of the PDCP layer.

It should be noted that the PDUs in the sent queue of the PDCP layer specifically include two types of data: PDUs to be sent to the UE to which the PDCP SN has been added and PDUs to be sent to the UE to be confirmed.

Among them, the PDUs that have been added PDCP SN to be sent to the UE include the packets that have added the PDCP SN protocol header, are to be processed by other protocol layers (RLC layer or MAC layer), and the PDCP SN protocol header has been added, and other protocols Packets that have been processed by the layer but not yet sent to the UE.

Stripping the protocol header refers to the process of removing the SDAP and PDCP headers added in front of the IP message, which is the inverse process of the protocol header adding process. As shown in FIG. 4, it is a schematic diagram of protocol header processing provided by an embodiment of the present disclosure. Stripping off the protocol header is specifically to point the data start position to the first byte of the IP message, that is, move from the data start position PstData1 to the PstData position. Among them, N is the size of the SDAP protocol header, and M is the size of the PDCP SN protocol header. PstData is the position of the first byte of the application layer IP packet.

After the source base station strips off the protocol header of the PDU in the sent queue of the PDCP layer, an IP packet carrying TCP data is formed, that is, the downlink forwarding data. Then, the source base station forwards the downlink forward data to the target base station through the channel established in the handover preparation phase, so that the target base station performs repetition processing on the downlink forward data according to the received feedback of the TCP layer and sends it to The UE realizes that the messages that will be sent to the UE to be confirmed by the UE and the messages that have been processed by the PDCP protocol layer are no longer discarded.

Step 102: Forward the downlink data from the core network to the target base station through the forwarding channel, and terminate the forwarding after receiving a message indicating the completion of data transmission sent by the core network, so that the target base station can transfer the data to the target base station. The downlink data from the core network is sent to the UE.

Specifically, the source base station forwards the protocol-processed packets to the target base station when the handover occurs, and then forwards the new data issued by the core network to the target base station until it receives a message from the core network to indicate the completion of the data transmission. The forwarding is terminated after the message, which means that the core network has completed the data transmission on the source side.

In one embodiment, the message used to indicate the completion of data transmission is specifically an ENDMARK message.

The implementation method of the 4G and 5G network inter-switching provided by the embodiments of the present disclosure implements the reverse protocol processing process on the packets that have been protocol-processed on the source side during the switching execution phase, strips off the PDCP PDU two-layer protocol header, and forms the original IP packet The text is transmitted to the target base station through the forward link for priority transmission, and at the TCP level at the target base station side, the repeated transmission of the message on the air interface is minimized, which can achieve lossless forwarding when switching data, thereby ensuring the stability of the transmission rate.

On the basis of the foregoing embodiment, the process of stripping the protocol header of the PDU in the sent queue of the PDCP layer is specifically as follows:

Specifically, SN is the sequence number of the PDU to which PDCP SN is added.

If the UE is in a 4G network, the PDCP SN accumulated in the PDCP layer is stripped of the PDCP SN according to the order of the PDU position, where pdcp-SN-Size is the size of 4G PDCP SN to form an IP packet carrying TCP data Then, the IP message is forwarded to the target base station through the forwarding channel established in the handover preparation phase.

At this time, the position sequence of the PDU is determined according to the size of the SN and 4G PDCP SN. In one embodiment, the position sequence of the PDU is specifically SN% [2 ^{[pdcp-SN-Size]} – 1] from small to large The order of pdcp-SN-Size is the size of 4G PDCP SN.

If the UE is in a 5G network, since the 5G network adds the service data adaptation protocol SDAP protocol layer, for the accumulated PDUs in the PDCP layer with PDCP SN added, according to the order of the PDU position, first strip off the PDCP SN, and then strip off the SDAP protocol Header, the SDAP protocol header and PDCP SN added before the IP message are removed to form an IP message carrying TCP data, and then the IP message is forwarded to the target base station through the forwarding channel established in the handover preparation phase.

At this time, the position sequence of the PDU is determined according to the size of the SN and the 5G PDCP SN. In an embodiment, the position sequence of the PDUs is specifically the SN%[2 ^{[pdcp-SN-Size]} -1] sequence from small to large, where pdcp-SN-Size is the size of the 5G PDCP SN.

The method for implementing the switchover between 4G and 5G networks provided by the embodiments of the present disclosure is to obtain IP packets carrying TCP data by stripping off the access network protocol header, and forward the packets that have been protocol-processed on the source side when the switchover occurs. To the target base station, it is possible to reduce the problem of the rate drop on the target base station side caused by the discarding of TCP packets.

As shown in FIG. 5, a schematic flow chart of the method for implementing mutual handover between 4G and 5G networks provided by an embodiment of the present disclosure, which is applied to a target base station, includes:

Step 200: When the target base station receives the handover complete message sent by the user terminal UE, it sends the downlink forwarding data received through the forwarding channel to the UE, and schedules the uplink data. If the uplink data is received, it is based on the transmission control protocol TCP Layer receiving feedback to perform deduplication processing on the downlink forward data, and send the downlink forward data after deduplication processing to the UE;

Specifically, when the UE completes the handover between 4G and 5G networks, when the UE after the handover is in 4G, the target base station receives the HO Complete message sent by the UE, and when the UE is in 5G, the target base station receives the HO to NR-RAN Confirm of the UE information.

When the target base station receives the handover completion message sent by the user terminal UE, it starts to send the downlink forward data received through the forward channel to the UE, and schedules the uplink data. If the target base station receives the uplink data, it will follow the transmission control protocol The reception feedback of the TCP layer performs deduplication processing on the downlink forwarding data, and sends the downlink forwarding data after deduplication processing to the UE. The purpose of performing repetition processing according to the receiving feedback of the TCP layer is to delete the packets that the UE has successfully received, that is, to minimize redundant air interface transmission.

Step 201: After the downlink forwarding data is sent, the downlink data from the core network is sent to the UE;

Specifically, after the transmission of the downlink forwarding data is completed, the target base station transmits the downlink data from the core network to the UE through the air interface.

In the method for implementing mutual handover between 4G and 5G networks provided by the embodiments of the present disclosure, after receiving the downlink forward data obtained after the source base station strips off the protocol header of the PDUs in the transmitted queue of the PDCP layer, the downlink forward data The data is transferred for repetition processing, and the messages that the UE has successfully received are deleted. In the process of switching between 4G and 5G, the lossless transmission of data is maintained while the air interface redundant transmission is reduced, thereby ensuring the stability of the transmission rate.

On the basis of the above-mentioned embodiment, the processing of repetition processing on the downlink forward data according to the received feedback of the TCP layer specifically includes:

According to the message sequence number and feedback sequence number of the TCP feedback packet corresponding to the current thread identifier, and the message sequence number and feedback sequence number of the downlink data packet, it is judged whether the pre-defined deduplication processing condition is satisfied, and if it is satisfied, all the messages are deleted. Describe the downlink data packet;

Specifically, for the received multiple uplink TCP feedback packets, analyze the multiple uplink TCP feedback packets, and record the message sequence number Seq _j and the feedback sequence number AckSeq _j _{corresponding to the thread identifier Thread i} in the parsed TCP feedback packet;

_{Analyze the message sequence number Seq i} and the feedback sequence number AckSeq _i of the downlink data packet corresponding to the same thread identifier Thread _i to be sent;

Delete the downlink data packets that meet the pre-defined deduplication processing conditions;

In an embodiment, the pre-defined deweighting processing condition is specifically: (((Seq _i +L _i )%2^31<AckSeq _j )&&(abs(AckSeq _j -Seq _i -L _i )<2 ^ 31)) == 1, L i is the packet of the downlink data packet length, Seq _i downlink data packet to the packet sequence number, AckSeq _i downlink data packet to said feedback number, Seq _j is the The message sequence number _{of the TCP feedback packet, and AckSeq j} is the feedback sequence number of the TCP feedback packet;

Wherein, the thread identifier Thread _i is generated according to the source IP address SrcIP, the destination IP address DestIP, the source port address SrcPort, and the destination port address DstPort in the TCP feedback packet.

The implementation method for switching between 4G and 5G networks provided by the embodiments of the present disclosure provides specific deduplication processing conditions, which is simple and easy to implement.

On the basis of the foregoing embodiment, the implementation method of the 4G and 5G network inter-switching further includes:

Specifically, when the target base station receives the handover complete message sent by the user terminal UE, it sends the downlink forwarding data received through the forwarding channel to the UE, and schedules the uplink data. If the target base station has not received the uplink data, then Send all the downlink forward data received through the forward channel to the UE. Even if the sent downlink forward data has been received by the UE on the source side, the UE will exclude repeated discards at the TCP layer. The judgment is based on the TCP message Message sequence number Seq, and send ACK to inform the sender that it has been received

In the method for implementing mutual handover between 4G and 5G networks provided by the embodiments of the present disclosure, when the target base station does not receive uplink data, it directly sends all the downlink forwarding data received through the forwarding channel to the UE, ensuring the 4G and 5G switching Lossless transmission of time messages.

The following uses a specific example to illustrate the implementation method of the 4G and 5G network inter-switching provided by the embodiments of the present disclosure.

The UE accesses 4G and receives packets a1 a2 a3 a4 a5 a6 a7, where the number is the PDCP SN sequence number. Assuming that packets a1, a2, and a3 have been sent to the UE, a4, a5, a6, and a7 are added with PDCP SN and then processed and sent to RLC for MAC scheduling. At this time, a handover occurs, and the UE uplink confirms the receipt of a1, the UE receives a2 but does not confirm, and does not receive a3. At this time, it continues to receive bc d e packets from the core network. As the handover occurs, the 4G base station forwards a2 a3 a4 a5 a6 a7 b c d e to the 5G base station. After the UE switches to 5G, the TCP layer reports that a2 is received and expects to receive a3. At this time, the 5G base station will first send packets a3 a4 a5 a6 a7 that are not successfully delivered on the source air interface and are not delivered on the air interface due to the TCP layer report a2 received, and then send b c d e packets after the transmission is completed. This ensures that the TCP layer is transmitted in order and no packet loss, so the rate can remain unchanged before and after the switch.

As shown in FIG. 6, a schematic structural diagram of an apparatus for implementing mutual handover between 4G and 5G networks provided by an embodiment of the present disclosure includes: a forwarding channel establishment module 610, a first forwarding module 620, and a second forwarding module 630, where ,

The forward passage establishing module 610 is used to establish the forward passage during the handover preparation stage;

Specifically, forwarding is forward. In the handover preparation phase, the forwarding channel establishment module 610 establishes a forwarding link between the 5G access network NR-RAN and the core network 5GC, and the 4G access network E-UTRAN and the core network EPC. .

The first forwarding module 620 is used to send a handover command to the user terminal UE during the handover execution phase to strip the protocol header of the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol to form a downlink forwarding Data, the downlink forward data is forwarded to the target base station through the forward channel, so that the target base station performs repetition processing on the downlink forward data according to the reception feedback of the TCP layer of the transmission control protocol and then sends it to UE;

Specifically, in the handover execution phase, the first forwarding module 620 sends a handover command to the user terminal UE. After the UE receives the handover command from the source base station, it will perform a network handover operation. If the UE is currently in a 4G network, it will switch to a 5G network. , If the UE is currently in a 5G network, switch to a 4G network.

When the UE is on a 4G network, the handover command sent by the first forwarding module 620 to the UE is specifically a HOFrom E-UTRAN Command message; when the UE is on a 5G network, the handover command sent by the source base station to the UE is a HO Command message.

After the first forwarding module 620 sends a handover command to the user terminal UE, it strips off the protocol header of the packet that has been protocol-processed on the source side when the handover occurs and forwards it to the target base station.

Specifically, the packets that have been protocol-processed on the source side refer to the PDUs in the sent queue of the PDCP layer.

Stripping the protocol header refers to the process of removing the SDAP and PDCP headers added in front of the IP message, which is the inverse process of the protocol header adding process.

After the first forwarding module 620 strips off the protocol header of the PDU in the sent queue of the PDCP layer, an IP packet carrying TCP data is formed, that is, the downlink forwarding data. Then, forward the downlink forward data to the target base station through the channel established in the handover preparation phase, so that the target base station performs repetition processing on the downlink forward data according to the received feedback of the TCP layer and sends it to the UE, It is realized that the messages that will be sent to the UE to be confirmed by the UE and the messages that have been processed by the PDCP protocol layer are no longer discarded.

The second forwarding module 630 is configured to forward the downlink data from the core network to the target base station through the forwarding channel, and terminate the forwarding after receiving a message indicating the completion of data transmission sent by the core network. For the target base station to send the downlink data from the core network to the UE.

Specifically, the second forwarding module 630 forwards the new data issued by the core network to the target base station until it terminates the forwarding after receiving a message sent by the core network for indicating the completion of data transmission, indicating that the core network is in the source side data Sending is complete.

The device for implementing mutual handover between 4G and 5G networks provided by the embodiments of the present disclosure performs a reverse protocol processing process on the packets that have been protocol-processed on the source side during the handover execution phase, strips off the PDCP PDU two-layer protocol header, and forms the original IP packet The text is transmitted to the target base station through the forward link for priority transmission, and at the TCP level at the target base station side, the repeated transmission of the message on the air interface is minimized, which can achieve lossless forwarding when switching data, thereby ensuring the stability of the transmission rate.

On the basis of the foregoing embodiment, the first forwarding module is specifically configured to:

The device for implementing inter-switching between 4G and 5G networks provided by the embodiments of the present disclosure is used to implement the foregoing method embodiments for implementing inter-switching between 4G and 5G networks. Therefore, the descriptions and definitions in the foregoing method embodiments can be used in this The understanding of each functional module in the disclosed embodiment will not be repeated here.

As shown in FIG. 7, a schematic structural diagram of a device for implementing mutual handover between 4G and 5G networks provided by an embodiment of the present disclosure, including: a weight removal processing module 710 and a first sending module 720, where:

The repetition processing module 710 is configured to send the downlink forwarding data received through the forwarding channel to the UE when the handover complete message sent by the user terminal UE is received, and to schedule the uplink data. If the uplink data is received, according to the transmission The received feedback of the TCP layer of the control protocol performs repetition processing on the downlink forward data, and sends the downlink forward data after repetition processing to the UE;

Specifically, when the UE completes the handover between 4G and 5G networks, when the UE after the handover is in 4G, the deduplication processing module 710 receives the HO Complete message sent by the UE. When the UE is in 5G, the deduplication processing module 710 receives the UE’s HO to NR-RAN Confirm message.

When the deduplication processing module 710 receives the handover completion message sent by the user terminal UE, it starts to send the downlink forward data received through the forwarding channel to the UE, and schedules the uplink data. If the deduplication processing module 710 receives the uplink data , Performing repetition processing on the downlink forward data according to the reception feedback of the TCP layer of the transmission control protocol, and sending the downlink forward data after repetition processing to the UE. The purpose of performing repetition processing according to the receiving feedback of the TCP layer is to delete the packets that the UE has successfully received, that is, to minimize redundant air interface transmission.

The first sending module 720 is configured to send the downlink data from the core network to the UE after the sending of the downlink forwarding data is completed;

Specifically, after the sending of the downlink forwarding data is completed, the first sending module 720 sends the downlink data from the core network to the UE through the air interface.

The device for implementing mutual handover between 4G and 5G networks provided by the embodiments of the present disclosure, after receiving the downlink forward data obtained after the source base station strips off the protocol header of the PDUs in the sent queue of the PDCP layer, the downlink forward data The data is transferred for repetition processing, and the messages that the UE has successfully received are deleted. In the process of switching between 4G and 5G, the lossless transmission of data is maintained while the air interface redundant transmission is reduced, thereby ensuring the stability of the transmission rate.

On the basis of the foregoing embodiment, the weight removal processing module is specifically configured to:

On the basis of the foregoing embodiment, the device for implementing mutual handover between 4G and 5G networks further includes:

FIG. 8 is a schematic structural diagram of a network-side device provided by an embodiment of the disclosure. As shown in FIG. 8, the network-side device 800 may include at least one processor 810, a memory 820, at least one user interface 830, and a transceiver 840. The various components in the network side device 800 are coupled together through the bus system 850. It can be understood that the bus system 850 is used to implement connection and communication between these components. In addition to the data bus, the bus system 850 also includes a power bus, a control bus, and a status signal bus. However, for the sake of clarity, various buses are marked as the bus system 850 in FIG. 8. The bus system may include any number of interconnected buses and bridges, specifically one or more processors represented by the processor 810 and the memory 820 The various circuits of the representative memory are linked together. The bus system can also link various other circuits such as peripherals, voltage regulators, and power management circuits. These are all known in the art. Therefore, the embodiments of the present disclosure will not further describe them. . The bus interface provides the interface. The transceiver 840 may be a plurality of elements, including a transmitter and a receiver, and provide a unit for communicating with various other devices on the transmission medium. For different user equipment, the user interface 830 may also be an interface capable of connecting externally and internally with the required equipment. The connected equipment includes but not limited to a keypad, a display, a speaker, a microphone, a joystick, and the like.

It can be understood that the memory 820 in the embodiment of the present disclosure may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory. Among them, the non-volatile memory can be read-only memory (Read-Only Memory, ROM), programmable read-only memory (Programmable ROM, PROM), erasable programmable read-only memory (Erasable PROM, EPROM), and electrically available Erase programmable read-only memory (Electrically EPROM, EEPROM) or flash memory. The volatile memory may be Random Access Memory (RAM), which is used as an external cache. By way of exemplary but not restrictive description, many forms of RAM are available, such as static random access memory (Static RAM, SRAM), dynamic random access memory (Dynamic RAM, DRAM), synchronous dynamic random access memory (Synchronous DRAM, SDRAM), Double Data Rate Synchronous Dynamic Random Access Memory (Double Data Rate SDRAM, DDRSDRAM), Enhanced Synchronous Dynamic Random Access Memory (Enhanced SDRAM, ESDRAM), Synchronous Link Dynamic Random Access Memory (Synchlink DRAM, SLDRAM) And Direct Rambus RAM (DRRAM). The memory 820 described in various embodiments of the present disclosure includes, but is not limited to, these and any other suitable types of memory.

The processor 810 is responsible for managing the bus system and general processing. The memory 820 may store computer programs or instructions used by the processor 810 when performing operations. Specifically, in one embodiment, the processor 810 executes the computer program when the computer program is executed. The steps of implementing the aforementioned method for implementing mutual handover between 4G and 5G networks, for example, include:

In the handover preparation phase, the source base station establishes a forward channel;

The downlink data from the core network is forwarded to the target base station through the forwarding channel, and the forwarding is terminated after receiving the message indicating the completion of data transmission sent by the core network, so that the target base station can transfer the data from the target base station. The downlink data of the core network is sent to the UE. or,

When receiving the handover completion message sent by the user terminal UE, the downlink forward data received through the forward channel is sent to the UE, and the uplink data is scheduled. Performing deduplication processing on the downlink forwarding data, and sending the downlink forwarding data after deduplication processing to the UE;

The method steps disclosed in the foregoing embodiments of the present disclosure may be applied to the processor 810 or implemented by the processor 810. The processor 810 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the foregoing method may be completed by an integrated logic circuit of hardware in the processor 810 or instructions in the form of software. The aforementioned processor 810 may be a general-purpose processor, a digital signal processor (Digital Signal Processor, DSP), an application specific integrated circuit (ASIC), a ready-made programmable gate array (Field Programmable Gate Array, FPGA) or other Programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps, and logical block diagrams disclosed in the embodiments of the present disclosure can be implemented or executed. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor or the like. The steps of the method disclosed in the embodiments of the present disclosure may be directly embodied as being executed and completed by a hardware decoding processor, or executed and completed by a combination of hardware and software modules in the decoding processor. The software module can be located in a mature storage medium in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers. The storage medium is located in the memory 820, and the processor 810 reads the information in the memory 820, and completes the steps of the foregoing method in combination with its hardware.

It can be understood that the embodiments described in the present disclosure can be implemented by hardware, software, firmware, middleware, microcode, or a combination thereof. For hardware implementation, the processing unit can be implemented in one or more application specific integrated circuits (ASIC), digital signal processor (Digital Signal Processing, DSP), digital signal processing equipment (DSP Device, DSPD), programmable Logic Device (Programmable Logic Device, PLD), Field-Programmable Gate Array (Field-Programmable Gate Array, FPGA), general-purpose processors, controllers, microcontrollers, microprocessors, and others for performing the functions described in this application Electronic unit or its combination.

For software implementation, the described technology can be implemented by modules (for example, procedures, functions, etc.) that perform the functions described in the embodiments of the present disclosure. The software codes can be stored in the memory and executed by the processor. The memory can be implemented in the processor or external to the processor.

The network-side device provided by the embodiment of the present disclosure performs the reverse protocol processing process on the packets that have been protocol-processed on the source side during the handover execution phase, strips off the PDCP and PDU two-layer protocol headers, forms the original IP packet, and passes the forward chain It is transmitted to the target base station first, and repeated transmission of packets on the air interface is minimized at the TCP level on the target side, which can realize lossless forwarding when switching data, thereby ensuring the stability of the transmission rate.

The embodiments of the present disclosure also provide a non-transitory computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the implementation method for switching between 4G and 5G networks provided by the foregoing method embodiments is implemented. Examples include: in the handover preparation phase, the source base station establishes a forwarding channel; in the handover execution phase, the source base station sends a handover command to the user terminal UE to strip the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol The protocol header is processed to form downlink forwarding data, and the downlink forwarding data is forwarded to the target base station through the forwarding channel, so that the target base station can forward the downlink according to the received feedback of the TCP layer of the transmission control protocol The data is sent to the UE after deduplication processing; the downlink data from the core network is forwarded to the target base station through the forwarding channel, and the forwarding is terminated after receiving the message indicating the completion of the data transmission sent by the core network, So that the target base station sends the downlink data from the core network to the UE.

The embodiments of the present disclosure also provide a non-transitory computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the implementation method for switching between 4G and 5G networks provided by the foregoing method embodiments is implemented. For example, when the target base station receives the handover completion message sent by the user terminal UE, it sends the downlink forwarding data received through the forwarding channel to the UE, and schedules the uplink data. If the uplink data is received, it is based on the transmission control protocol TCP The receiving feedback of the layer performs repetition processing on the downlink forward data, and sends the downlink forward data after repetition processing to the UE; after the downlink forward data transmission is completed, to the The UE sends downlink data from the core network; wherein, the downlink forward data is obtained after the source base station strips off the protocol header of the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol.

The device embodiments described above are merely illustrative, where the units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, they may be located in One place, or it can be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the objectives of the solutions of the embodiments. Those of ordinary skill in the art can understand and implement without creative work.

Through the description of the above implementation manners, those skilled in the art can clearly understand that each implementation manner can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution essentially or the part that contributes to the existing technology can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM/RAM, magnetic A disc, an optical disc, etc., include a number of instructions to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiment.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, but not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions recorded in the foregoing embodiments are modified, or some of the technical features are equivalently replaced; these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

A method for implementing mutual handover between 4G and 5G networks, which is characterized in that it includes:

In the handover preparation phase, the source base station establishes a forward channel;

In the handover execution stage, the source base station sends a handover command to the user terminal UE, strips off the protocol header of the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol, and forms the downlink forward data. The forwarded data is forwarded to the target base station through the forwarding channel, so that the target base station performs repetition processing on the downlink forwarded data according to the received feedback of the TCP layer of the transmission control protocol and then sends it to the UE;

The downlink data from the core network is forwarded to the target base station through the forwarding channel, and the forwarding is terminated after receiving the message indicating the completion of data transmission sent by the core network, so that the target base station can transfer the data from the target base station. The downlink data of the core network is sent to the UE.
The method for implementing mutual handover between 4G and 5G networks according to claim 1, wherein the PDUs in the sent queue of the PDCP layer specifically include: PDUs to be sent to the UE to which the PDCP sequence number SN has been added and The PDU that has been sent to the UE to be confirmed.
The method for implementing mutual handover between 4G and 5G networks according to claim 2, characterized in that, the process of stripping the protocol header of the PDU in the sent queue of the PDCP layer is specifically:

If the UE is in a 4G network, the PDCP SN accumulated in the PDCP layer with PDCP SN added is stripped according to the position order of the PDU, where the position order of the PDU is determined according to the size of the SN and 4G PDCP SN; or,

If the UE is in a 5G network, the PDCP SN accumulated in the PDCP layer is added to the PDCP layer, according to the position order of the PDU, first strip off the PDCP SN, and then strip off the service data adaptation protocol SDAP protocol header, where the position of the PDU The order is determined according to the size of SN and 5G PDCP SN.
A method for implementing mutual handover between 4G and 5G networks, which is characterized in that it includes:

When the target base station receives the handover complete message sent by the user terminal UE, it sends the downlink forwarding data received through the forwarding channel to the UE, and schedules the uplink data. If the uplink data is received, it is received according to the TCP layer of the transmission control protocol. Feedback to perform deduplication processing on the downlink forward data, and send the downlink forward data after deduplication processing to the UE;

Sending the downlink data from the core network to the UE after the transmission of the downlink forwarding data is completed;

Wherein, the downlink forwarding data is obtained after the source base station strips off the protocol header of the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol.
The method for implementing mutual handover between 4G and 5G networks according to claim 4, characterized in that said performing repetition processing on said downlink forwarding data according to the received feedback of the TCP layer specifically comprises:

For the received multiple uplink TCP feedback packets, analyze the multiple uplink TCP feedback packets to obtain the message sequence number and the feedback sequence number of the TCP feedback packet corresponding to each thread identifier;

For each thread ID, parse the downlink data packet to be sent corresponding to the current thread ID, and obtain the message sequence number and the feedback sequence number of the downlink data packet;

According to the message sequence number and feedback sequence number of the TCP feedback packet corresponding to the current thread identifier, and the message sequence number and feedback sequence number of the downlink data packet, it is judged whether the pre-defined deduplication processing condition is satisfied, and if it is satisfied, all the messages are deleted. Describe the downlink data packet.
The method for implementing mutual handover between 4G and 5G networks according to claim 4, further comprising:

If the uplink data is not received, all the downlink forward data received through the forward channel are sent to the UE.
A device for implementing mutual handover between 4G and 5G networks, which is characterized in that it includes:

The forwarding channel establishment module is used to establish the forwarding channel during the handover preparation phase;

The first forwarding module is used to send a handover command to the user terminal UE during the handover execution phase to strip the protocol header of the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol to form downlink forward data , Forwarding the downlink forwarding data to the target base station through the forwarding channel, so that the target base station performs repetition processing on the downlink forwarding data according to the received feedback of the TCP layer of the transmission control protocol and then sends it to the UE ；

The second forwarding module is used to forward the downlink data from the core network to the target base station through the forwarding channel, until it terminates the forwarding after receiving a message indicating the completion of data transmission sent by the core network for The target base station sends the downlink data from the core network to the UE.
The device for implementing mutual handover between 4G and 5G networks according to claim 7, wherein the PDUs in the sent queue of the PDCP layer specifically include: PDUs to be sent to the UE to which the PDCP sequence number SN has been added and The PDU that has been sent to the UE to be confirmed.
The device for implementing mutual handover between 4G and 5G networks according to claim 8, wherein the first forwarding module is specifically configured to:

If the UE is in a 4G network, the PDCP SN accumulated in the PDCP layer with PDCP SN added is stripped according to the position order of the PDU, where the position order of the PDU is determined according to the size of the SN and 4G PDCP SN; or,

If the UE is in a 5G network, the PDCP SN accumulated in the PDCP layer is added to the PDCP layer, according to the position order of the PDU, first strip off the PDCP SN, and then strip off the service data adaptation protocol SDAP protocol header, where the position of the PDU The order is determined according to the size of SN and 5G PDCP SN.
A device for implementing mutual handover between 4G and 5G networks, which is characterized in that it includes:

The deduplication processing module is used to send the downlink forwarding data received through the forwarding channel to the UE when the handover complete message sent by the user terminal UE is received, and to schedule the uplink data, if the uplink data is received, according to the transmission control The received feedback of the protocol TCP layer performs deduplication processing on the downlink forward data, and sends the downlink forward data after deduplication processing to the UE;

The first sending module is configured to send the downlink data from the core network to the UE after the downlink forwarding data transmission is completed;

Wherein, the downlink forwarding data is obtained after the source base station strips off the protocol header of the protocol data unit PDU in the sent queue of the PDCP layer of the packet data convergence protocol.
The device for implementing mutual handover between 4G and 5G networks according to claim 10, wherein the de-duplication processing module is specifically configured to:

For the received multiple uplink TCP feedback packets, analyze the multiple uplink TCP feedback packets to obtain the message sequence number and the feedback sequence number of the TCP feedback packet corresponding to each thread identifier;

For each thread ID, parse the downlink data packet to be sent corresponding to the current thread ID, and obtain the message sequence number and the feedback sequence number of the downlink data packet;

According to the message sequence number and feedback sequence number of the TCP feedback packet corresponding to the current thread identifier, and the message sequence number and feedback sequence number of the downlink data packet, it is judged whether the pre-defined deduplication processing condition is satisfied, and if it is satisfied, all the messages are deleted. Describe the downlink data packet.
The device for implementing mutual handover between 4G and 5G networks according to claim 10, further comprising:

The second sending module is configured to send all the downlink forward data received through the forward channel to the UE if the uplink data is not received.
A network side device, comprising a memory, a processor, and a computer program stored on the memory and capable of running on the processor, wherein the processor executes the computer program to implement any one of claims 1 to 6 The steps of the method for implementing mutual handover between 4G and 5G networks.
A non-transitory computer-readable storage medium with a computer program stored thereon, characterized in that, when the computer program is executed by a processor, the realization of the 4G and 5G network switching as described in any one of claims 1 to 6 is realized Method steps.