KR20190081898A - Handover traffic transmitting method at traffic switching in multiple access network and network entity perorming the same - Google Patents

Abstract

Disclosed are a handover traffic transmission method in a multiple access network, and a network entity performing the same. When a terminal handovers from a first access network to a second access network, the network entity displays a first end marker on last traffic transmitted to the first access network to transmit the first end marker to the first access network, and may buffer second traffic, which is the traffic after the last traffic, among the traffic to be transmitted to the terminal. In addition, the network entity receives a second end marker from the first access network and may transmit the second traffic to the second access network after receiving the second end marker.

Description

HANDOVER TRAFFIC TRANSMITTING METHOD AT TRAFFIC SWITCHING IN MULTIPLE ACCESS NETWORK AND NETWORK ENTITY PERORMING THE SAME BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a handover traffic transmission method in a multiple access network and a network entity for performing the same.

The existing 3GPP Evolved Packet System (EPS) provides a seamless user experience when the UE moves beyond the coverage of the source base station (eNB) to the coverage of the target base station. The 3GPP EPS creates a forwarding tunnel between the source base station and the target base station through the X2 interface and transmits a packet that can not be transmitted to the source base station to the target base station at the time of handover. The target base station buffers the packet received from the source base station until the terminal completes the connection to the target base station.

On the other hand, when the gateway switches the packet path from the source base station to the target base station, the gateway transmits the end marker as the last packet to the source base station. The target base station transmits the packet received from the source base station to the terminal at the time when the terminal is connected. The target base station can receive the end marker through the forwarding tunnel and recognize the completion of the forwarded packet through the source base station. At this time, the target base station transmits the packet received from the gateway to the terminal. In such a 3GPP Intra-RAT (Radio Access Technology) handover, data between the UE and the gateway is transmitted through two different paths. An end marker is used to guarantee the order of the packets transmitted through the two paths.

In order to solve the problem of ensuring the order of the packets occurring during handover between not only Intra-RAT but also heterogeneous radio access systems, a GRE empty packet is utilized or a UE-based end marker transmission technique is proposed have.

On the other hand, next generation mobile communication system after EPC is expected to converge various access networks, and it is expected that multiple access networks will be connected at the same time.

SUMMARY OF THE INVENTION The present invention provides a method of guaranteeing a traffic transmission order at the time of handover in a multiple access network environment.

According to an embodiment of the present invention, there is provided a method for a network entity to transmit traffic when a terminal is handing over from a first access network to a second access network. The method includes displaying a first end marker on the last traffic transmitted to the first access network and transmitting the first end marker to the first access network, The method comprising the steps of: buffering a second traffic that is traffic, receiving a second end marker from the first access network, and transmitting the second traffic to the second access network after receiving the second end marker . ≪ / RTI >

The first access network may transmit the second end marker to the network entity after transmitting the last traffic to the terminal.

The method may further comprise performing a Protocol Data Unit (PDU) session establishment procedure for the second access network, wherein the step of transmitting to the first access network after the PDU session establishment procedure may be performed .

The network entity may be a user plane function.

The first access network may be a 3GPP access network and the second access network may be a Non-3GPP access network.

The terminal may be both connected to the first and second access networks.

According to another embodiment of the present invention, a method is provided in which, when a terminal hand over from a first access network to a second access network, the network entity transmits the traffic. The method includes measuring a first transmission delay time that is a transmission delay time for a first path formed on the network entity, the first access network, and the terminal, Measuring a second transmission delay time, which is a transmission delay time for a second path formed on the terminal, and performing path switching for performing the handover using the first and second transmission delay times Comprising the steps of: determining a required buffering time; buffering a first traffic that is traffic to be transmitted to the second access network during the buffering time; and transmitting the first traffic to the second access network after the buffering time can do.

The first transmission delay time may correspond to the round trip time generated in the first path, and the second transmission delay time may correspond to the round trip time generated in the second path.

일 수 있다. If the round trip time (RTT_ _3g) of the first path to the second round trip time is greater than (RTT_n _3g), the buffering time is

Lt; / RTI >

If the round trip time (RTT_ _3g) of the first path is equal to the second round trip time (RTT_n _3g) of the route or less, the buffering time may be zero.

The network entity may be a User Plane Function (UPF), and the UPF or the UE may measure the measurement of the first and second transmission delay times.

The round trip time of the first path and the round trip time of the second path may be measured using Internet Control Message Protocol (ICMP) ping.

The first access network may be a 3GPP access network and the second access network may be a Non-3GPP access network.

In accordance with another embodiment of the present invention, a network entity is provided for processing control signals on a network. Wherein the network entity comprises: a communication module for switching and transmitting traffic when the terminal performs handover from a first access network to a second access network; a network entity, a first access network, and a first Measuring a first round trip time as a round trip time for the route and measuring a second round trip time as a round trip time for the network entity, the second access network, and a second path formed on the terminal, A processor for determining a buffering time required for path switching for performing the handover using the first round trip time and the second round trip time, and a processor for, during the buffering time, For example.

The communication module may transmit the first traffic to the second access network after the buffering time.

일 수 있다. If the first round trip time (RTT_ _3g) is larger than the second round trip time (RTT_n _3g), the buffering time is

Lt; / RTI >

If equal to said first round trip time (RTT_ _3g) are the first 2 (RTT_n _3g) round-trip time or less, the buffering time may be zero.

The first and second round trip times may be measured using Internet Control Message Protocol (ICMP) Ping.

The network entity may be a User Plane Function (UPF), the first access network may be a 3GPP access network, and the second access network may be a Non-3GPP access network.

According to the embodiment of the present invention, it is possible to provide a continuous service to a user by ensuring a packet transmission order at the time of handover between access terminals and multiple access terminals.

1 is a diagram illustrating a 5G communication system according to an embodiment of the present invention.
2 is a diagram illustrating a traffic flow when a terminal according to an embodiment of the present invention accesses two access networks at the same time.
3 is a flowchart illustrating a method of ensuring a transmission order of traffic according to an embodiment of the present invention.
4 is a diagram illustrating a method of ensuring the transmission order of traffic according to another embodiment.
5 is a block diagram illustrating a network entity according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, a terminal is referred to as a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station ), A subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT), a user equipment (UE) AMS, HR-MS, SS, PSS, AT, UE, and the like.

Also, a base station (BS) is an advanced base station (ABS), a high reliability base station (HR-BS), a node B, an evolved node B, eNodeB), an access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR) BS, ABS, Node B, eNodeB, AP, RAS, BTS, MMR-BS, RS, and so on) , HR-RS, and the like.

In the following description, an Inter-RAT handover method is described in a 5G wireless communication system environment that accommodates two radio access networks (RATs) having different RAT (Radio Access Network) types. have.

1 is a diagram illustrating a 5G communication system according to an embodiment of the present invention.

1, a 5G communication system 1000 according to an embodiment of the present invention includes a terminal 100, a 3GPP access network 210, a Non-3GPP Interworking Function (N3IWF) 220, a Non-3GPP access network 230, an access and mobility management function (AMF) 320, a session management function (SMF) 330, a user plane function (UPF) 310, And a data network (DN) 400. Here, the N3 IWF 220 and the Non-3GPP access network 230 may be integrated with each other.

The AMF 320 and the SMF 330 are network entities that process control signals. The AMF 320 performs authentication, connection, and mobility control functions. The SMF 330 has a session control function (setting / changing / canceling of a session) and performs a signaling procedure for traffic path setting and traffic mobility management. That is, the SMF 330 controls the data path between the UPF 310 and the RANs 210 and 220. The AMF 320 has an N1 signal interface with a NAS (Non-access stratum) signal together with the AT 100. [

The UPF 310 is a network entity of a data plane that collectively accommodates multiple RANs via an N3 interface. The UPF 310 connects the data plane between the multiple access network (the 3GPPP access network N3IWF in FIG. 1) and the DN 400, and the traffic of the terminal 100 (i.e., the user) .

The UPF 310 and each of the RANs 210 and 220 receive the routing rules for the terminal 100 from the SMF 330 via N4 and N2 interfaces and perform the IP routing function through the received lighting rules.

As described above, the 5G communication system according to the embodiment of the present invention is an integrated structure that accommodates the 3GPP access network 210 and the Non-3GPP access network 230 at the same time. In addition, the handover according to the embodiment of the present invention described below assumes a multiple access network in which there is no direct interface for data forwarding between different RAN nodes.

2 is a diagram illustrating a traffic flow when a terminal according to an embodiment of the present invention accesses two access networks at the same time. More specifically, FIG. 2 shows the flow of traffic (data packet) on the user plane when the terminal concurrently accesses 3GPP access and Non-3GPP access.

The UPF 310 may simultaneously transmit traffic (data packets) to multiple paths that pass through a multiple access network when the traffic (data packet) that was transmitted in the existing 3GPP access is path-switched to the Non-3GPP access .

As shown in FIG. 2, the Nth data packet is transmitted to the terminal through the 3GPP access. The N + 1 and N + 2th data packets are transmitted through the 3GPP access network 210 while N + 3, N + 4 and N + 5 are transmitted through the Non-3GPP access network 230). At this time, the order of the packets (traffic) to be transmitted can be ensured due to a difference in transmission on the path between the UPF 310 and each access network, and a difference in transmission delay in the URN. On the other hand, there is no direct interface for data forwarding between the 3GPP access network 210 and the N3 IWF 220.

In this way, multipath occurs due to path switching, and the transmission order of traffic (data packet) needs to be ensured in such a situation. Hereinafter, a method of ensuring the transmission order of traffic (data packets) will be described with reference to FIGS. 3 and 4. FIG.

3 is a flowchart illustrating a method of ensuring a transmission order of traffic according to an embodiment of the present invention.

3, it is assumed that the terminal 100 connected to the 3GPP access network 210 is also connected to the N3 IWF 220, which is a non-3GPP access network.

First, the traffic provided by the data network (DN) 400 is transmitted to the terminal 100 via the UPF 310 and the 3GPP access network 210 (S310).

When the AT 100 moves to the non-3GPP access network, the AT 100 performs a PDU Session Establishment procedure with the AMF 320 and the SMF 330 (S320) .

During the PDU session establishment procedure with the non-3GPP access network, the UPF 310 receives an N4 Session Establishment Request message, which is a session request message from the SMF 330 to the new access network (S330 ).

The UPF 310 performs path switching from the existing 3GPP access network 210 to the non-3GPP access network 230 in the case of receiving the N4 session setup request message in step S330 (S340).

The UPF 310 buffers the traffic after the path switching without directly transmitting the traffic to the Non-3GPP access in order to ensure the order of the traffic (data packet) (S350).

The UPF 310 displays an end marker on the last traffic transmitted to the 3GPP access network 210 and transmits the end marker to the 3GPP access network 210 in step S360.

The 3GPP access network 210 transmits the traffic transmitted in step S360 to the terminal 100 through an end marker (S370).

The 3GPP access network 210 transmits an end marker to the UPF 310 in step S350 when the 3GPP access network 210 finishes transmitting the traffic to the end marker in step S370.

If the end marker is received in step S350, the UPF 310 transmits the buffered traffic to the N3 IWF 220 in step S350 in step S380. Then, the N3WIF 220 transmits the traffic received from the UPF 310 to the terminal 100 (S380).

According to the embodiment of the present invention, the transmission order of traffic (data packet) can be guaranteed by transmitting / receiving end markers bidirectionally between the UPF 310 and the access network.

4 is a diagram illustrating a method of ensuring the transmission order of traffic according to another embodiment.

4, it is assumed that the terminal 100 connected to the 3GPP access network 210 is also connected to the N3 IWF 220, which is a non-3GPP access network.

First, the traffic (data packet) provided in the data network 400 is transmitted to the terminal 100 via the UPF 310 and the 3GPP access network 210 (S410).

Next, the UPF 310 measures a round trip time on the multipath between the UPF 310 and the terminal 100 (S420). That is, the UPF 310 measures the round trip time on the 3GPP access network 210 path and the round trip time on the N3 IWF 220 path. Internet Control Message Protocol (ICMP) ping may be used to measure the round trip time. UPF 310 measures the round trip time to be sent on multiple paths using ICMP Ping. At this time, the measurement of the round trip time can be performed not only by the UPF 310 but also by the terminal 100 connected to each access network. When the terminal 100 measures the round trip time, it transmits the measured round trip time to the UPF 310. The round trip time is a value corresponding to the transmission delay occurring on the multipath. Meanwhile, the measured round trip time may be managed by the UPF 310 or managed by the AMF 320 or the SMF 330. When the measured round trip time is managed by the AMF 320 or the SMF 330, the AMF 320 or the SMF 330 adds a buffering request for path switching to the N4 Session Establishment Request message And transmits it to the UPF 310. [

The UPF 310 determines a buffering time required for path switching using the round trip time measured in step S420 (S430). RTT_ _3g is the round trip time (Round Trip Time) measured in the directions via a 3GPP access network (210), RTT_n _3g is a round trip measurement in directions via the Non-3GPP access network 230 (or 230) Time (Round Trip Time). In this case, the buffering time (Buffering_time) is determined according to the following Equation 1 (Algorithm).

이 된다. 라운드 트립 타임은 왕복 시간이므로, 버퍼링 시간은 (RTT__3g-RTT_n_3g)를 2로 나눈다. 이와 같은 버퍼링 시간은 UPF(310) 뿐만 아니라 AMF(320) 또는 SMF(330)에서 계산될 수 있다. As shown in the equation (1), when the RTT_ _{3g 3g} RTT_n equal to or smaller, buffering time (Buffering_time) is zero. In this case, since the transmission delay through the 3GPP access network 210 is smaller than the transmission delay via the non-3GPP access network 230, the order of data packets is guaranteed even if buffering time is not required. On the other hand, when greater than RTT_n RTT_ _{3g 3g,} buffering time (Buffering_time) is

. Since the round trip time is the round trip time, it divides the buffering time (RTT_ _3g -RTT_n _3g) 2. The buffering time may be calculated in the AMF 320 or the SMF 330, as well as in the UPF 310.

Meanwhile, when the AT 100 moves to a non-3GPP access network, the AT 100 performs a PDU Session Establishment procedure with the AMF 320 and the SMF 330 S440).

During the non-3GPP access and PDU session establishment procedures, the UPF 310 receives an N4 Session Establishment Request message, which is a session request message from the SMF 330 to a new access network (S450) .

The UPF 310 performs path switching of the traffic of the AT 100 from the existing 3GPP access network to the non-3GPP access network 220 or 230 when receiving the N4 session setup request message in step S450 (S460).

The UPF 310 buffers the traffic after the path switching without directly transmitting the traffic to the Non-3GPP access in order to guarantee the order of the traffic (data packet) (S470). At this time, the UPF 310 buffers traffic during the buffering time determined in step S430.

The UPF 310 transmits the traffic to the N3 IWF 220 after buffering the traffic for the buffering time determined in step S430 (S480). Then, the N3WIF 220 transmits the traffic received from the UPF 310 to the terminal 100 (S480).

According to another embodiment of the present invention, the transmission order of the traffic (data packet) can be guaranteed by measuring the transmission delay occurring on the multipath between the UPF 310 and the terminal 100 and performing buffering .

5 is a block diagram illustrating a network entity according to an embodiment of the present invention.

The network entity 500 in FIG. 5 may be the UPF 310, the AMF 320, or the SMF 330 of FIG.

As shown in FIG. 5, a network entity 500 according to an embodiment of the present invention includes a processor 510, a memory 520, and a communication module 530.

The processor 510 may be configured to implement the methods and functions described in FIG. 3 and FIG.

The memory 520 is coupled to the processor 510 and stores various information related to the operation of the processor 510. [

The communication module 530 transmits or receives signals with other entities.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (19)

A method for a network entity to transmit traffic when a terminal handing over from a first access network to a second access network,
Displaying a first end marker on the last traffic transmitted to the first access network and transmitting the first end marker to the first access network;
Buffering a second traffic that is traffic after the last traffic among the traffic to be transmitted to the terminal;
Receiving a second end marker from the first access network, and
And transmitting the second traffic to the second access network after receiving the second end marker. The method according to claim 1,
Wherein the first access network transmits the second end marker to the network entity after transmitting the last traffic to the terminal. The method according to claim 1,
Further comprising performing a Protocol Data Unit (PDU) session establishment procedure for the second access network,
Wherein the step of transmitting to the first access network after the PDU session establishment procedure is performed. The method according to claim 1,
Wherein the network entity is a user plane function. 5. The method of claim 4,
Wherein the first access network is a 3GPP access network and the second access network is a Non-3GPP access network. The method according to claim 1,
Wherein the terminal is both multi-connected to the first and second access networks. A method for a network entity to transmit traffic when a terminal handing over from a first access network to a second access network,
Measuring a first transmission delay time that is a transmission delay time for a first path formed on the network entity, the first access network, and the terminal,
Measuring a second transmission delay time that is a transmission delay time for the network entity, the second access network, and a second path formed on the terminal,
Determining a buffering time required for path switching for performing the handover using the first and second transmission delay times,
Buffering the first traffic, which is traffic to be transmitted to the second access network, during the buffering time, and
And transmitting the first traffic to the second access network after the buffering time. 8. The method of claim 7,
Wherein the first transmission delay time corresponds to a round trip time generated in the first path,
Wherein the second transmission delay time corresponds to a round trip time generated in the second path. 9. The method of claim 8,
If the round trip time (RTT_ _3g) of the first path to the second round trip time is greater than (RTT_n _3g), the buffering time is

/ RTI > 10. The method of claim 9,
If the round trip time of the first path (RTT_ _3g) is greater than the round trip time (RTT_n _3g) of the second path or smaller, the buffering time is zero method. 8. The method of claim 7,
The network entity is a user plane function (UPF)
Wherein the UPF or the UE measures the measurement of the first and second transmission delay times. 9. The method of claim 8,
Wherein the round trip time of the first path and the round trip time of the second path are measured using Internet Control Message Protocol (ICMP) ping. 8. The method of claim 7,
Wherein the first access network is a 3GPP access network and the second access network is a Non-3GPP access network. 1. A network entity for processing control signals on a network,
A communication module for switching and transmitting traffic when the terminal performs handover from the first access network to the second access network,
Measuring a first round trip time that is a round trip time for the network entity, the first access network, and the first path formed on the terminal, and determining a round trip time for the network entity, the second access network, Determining a buffering time required for path switching for performing the handover using the first round trip time and the second round trip time, measuring a second round trip time as a round trip time for the formed second path, , And
And a buffer for buffering the first traffic, which is traffic to be transmitted to the second access network, during the buffering time. 15. The method of claim 14,
Wherein the communication module transmits the first traffic to the second access network after the buffering time. 15. The method of claim 14,
If the first round trip time (RTT_ _3g) is larger than the second round trip time (RTT_n _3g), the buffering time is

In network entity. 17. The method of claim 16,
It said first round-trip-time (RTT_ _3g) the second case greater than the round trip time (RTT_n _3g) or less, the buffering time is zero network entity. 15. The method of claim 14,
Wherein the first and second round trip times are measured using Internet Control Message Protocol (ICMP) Ping. 15. The method of claim 14,
Wherein the network entity is a User Plane Function (UPF), the first access network is a 3GPP access network, and the second access network is a Non-3GPP access network.

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