COMMUNICATION METHOD AND SYSTEM FOR ESTABLISHING MULTIPLE SESSIONS - Patent application

Abstract

To provide a communication method and the like that can establish a plurality of sessions via a plurality of access points and gateways, suitable for a terminal to achieve large-capacity communication with one application server.SOLUTION: A communication method includes: a first step in which a terminal establishes a session with a proxy server for each arbitrary combination of an access point and a gateway in order to communicate with one application server; a second step in which the terminal branches one stream of packet series into a plurality of sessions and transmits them to the proxy server via the access point and the gateway for each session; and a third step in which the proxy server integrates packets received from a plurality of gateways via the plurality of sessions into one stream, and forwards the integrated one stream to the application server.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a technique for establishing a session in a mobile network core system of a mobile communication system. [Background technology]

[0002] Conventionally, in a mobile communication system, a terminal is accommodated in a mobile network core system of a communication carrier via a Radio Access Network (RAN) (see, for example, Non-Patent Documents 1 and 2). This system is composed of a control plane and a user plane. In recent years, the practical application of "Cell-free Massive MIMO (Multi Input Multi Output)" is expected as a 6th generation mobile communication system (see, for example, Non-Patent Documents 3 and 4). Massive MIMO, which is also provided in 5G, creates a coverage area like a spotlight for a moving terminal. Massive MIMO is further realized by the concept of Cell-free, which is created by one base station CPU (Central Processing Unit) and multiple access points. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS 23.501 V17.2.0, “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System architecture for the 5G System (5GS); Stage 2 (Release 17)” [Non-Patent Document 2] 3GPP TS 23.502 V17.2.1, “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Procedures for the 5G System (5GS); Stage 2 (Release 17)” [Non-Patent Document 3] IEEE Transactions on Wireless Communications (Volume: 16, Issue: 3, March 2017), "Cell-Free Massive MIMO Versus Small Cells" [Non-Patent Document 4] "What technologies will enable lifestyles in the Beyond 5G / 6G era?", KDDI Research, [online], [searched February 23, 2022], Internet<URL:https: / / www.itmedia.co.jp / mobile / articles / 2106 / 16 / news052.html> Summary of the Invention [Problem to be solved by the invention]

[0004] According to the above-mentioned Cell-free Massive MIMO, a terminal can simultaneously connect wireless links to a plurality of access points managed by a base station CPU. However, the question of which gateway a session with a terminal should be established with via a plurality of access points is merely a matter of implementation. The node through which a session between a terminal and an application server passes has a large effect on throughput. In particular, when multiple sessions can be established simultaneously, the effect is not only on the number of sessions but also on the combination of access points and gateways through which sessions pass. For example, if a terminal is to achieve a throughput of about 1 Tbps, it is generally assumed that multiple data flows are required. However, the throughput is greatly affected by which nodes in the user plane of the mobile network core system these data flows pass through.

[0005] Therefore, according to the present invention, a communication method for establishing multiple sessions via multiple access points and gateways, which is suitable for realizing large-volume communication between a terminal and one application server, is provided. and System M The purpose is to provide. [Means for solving the problem]

[0006] According to the present invention, a terminal Using the control device, A communication method for communicating with an application server via a plurality of access points, a plurality of gateways, and a proxy server, comprising: In order for a terminal to communicate with one application server, Transmitting a session establishment request including identifiers of a plurality of connectable access points to the control device; The control device selects an arbitrary combination of an access point and a gateway, and transmits an access point connection request including a list of the combination to the terminal; The terminal performs the above-mentioned combination via the access point and the gateway. a first step of establishing a session with a proxy server; a second step in which the terminal branches one stream of packets into a plurality of sessions and transmits each session to the proxy server via the access point and the gateway; a third step in which the proxy server aggregates packets received from multiple gateways through multiple sessions into one stream and forwards the aggregated stream to the application server; The present invention is characterized by having the following.

[0007] According to another embodiment of the communication method of the present invention, The control device further includes: Regarding the first step, A terminal transmits a session establishment request including identifiers of a plurality of connectable access points to a control device; The control device selects an arbitrary combination of an access point and a gateway, and transmits an access point connection request including a list of the combination to the terminal; The terminal establishes a session with the proxy server via the access point and the gateway for each combination. It is also preferable.

[0008] According to another embodiment of the communication method of the present invention, Regarding the first step, The session establishment request sent by the terminal further includes an application server address; The control device notifies the proxy server of the application server address, The proxy server establishes a connection with the application server based on the application server address; In the third step, the proxy server forwards the combined stream to the application server via the established connection. It is also preferable.

[0009] According to another embodiment of the communication method of the present invention, Regarding the first step, The control device selects all or a part of combinations from among all combinations (full mesh) of a plurality of access points to which the terminal can be connected and a plurality of gateways that can relay between the access points and the proxy server. It is also preferable.

[0010] According to another embodiment of the communication method of the present invention, The number of any combination of access points and gateways is selected so as not to exceed the maximum number of sessions per device. It is also preferable.

[0011] According to another embodiment of the communication method of the present invention, Among combinations of access points and gateways, a combination is selected that does not include an access point or gateway whose processing load rate or communication error rate exceeds a predetermined threshold. It is also preferable.

[0012] According to another embodiment of the communication method of the present invention, Among the combinations of access points and gateways, a combination is selected that does not include an access point or gateway whose processing load rate or communication error rate deviates from the average value by a predetermined rate or more. It is also preferable.

[0013] According to another embodiment of the communication method of the present invention, A stream is composed of multiple substreams with redundancy n. The multiple substreams are copies of a packet sequence from one stream. Each of the multiple sub-streams is transmitted to a session having a different combination of the access point and the gateway; When the proxy server receives a packet with a given sequence number from any of the different substreams for the first time, it considers that the packet with that sequence number has been received. It is also preferable.

[0014] According to another embodiment of the communication method of the present invention, The transmission speed is measured for each session consisting of a combination of an access point and a gateway. When the substream redundancy n is smaller than the number of sessions k (k>n), k C n Among the possible combinations, the combination with the highest sum of transmission rates for multiple sessions per stream is selected. It is also preferable.

[0015] According to the present invention, a terminal Using the control device,1. A system configured to communicate with an application server via a plurality of access points and a plurality of gateways and a proxy server, comprising: In order for a terminal to communicate with one application server, Transmitting a session establishment request including identifiers of a plurality of connectable access points to the control device; The control device selects an arbitrary combination of an access point and a gateway, and transmits an access point connection request including a list of the combination to the terminal; The terminal performs the above-mentioned combination via the access point and the gateway. Establish a session with the proxy server, A terminal establishes a session with a proxy server for each combination of an access point and a gateway in order to communicate with one application server; A terminal branches one stream of packets into a plurality of sessions and transmits each session to a proxy server via an access point and a gateway; The proxy server combines packets received from multiple gateways via multiple sessions into one stream and forwards the combined stream to the application server. It is characterized by: Effect of the Invention

[0019] Communication method according to the present invention and System To This makes it possible to establish multiple sessions via multiple access points and gateways, which is suitable for realizing large-volume communication between a terminal and one application server. [Brief description of the drawings]

[0020] [Figure 1] 1 is a configuration diagram of a mobile communication system according to the present invention. [Diagram 2] FIG. 2 is an explanatory diagram illustrating a session in the mobile communication system of FIG. [Diagram 3] FIG. 2 is a sequence diagram according to the present invention. [Figure 4] FIG. 11 is an explanatory diagram showing selection of a session according to the load factor of an access point and a gateway. [Diagram 5]FIG. 2 is an explanatory diagram showing the relationship between streams and sub-streams. [Figure 6] FIG. 11 is an explanatory diagram showing a combination of multiple substreams. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0022] FIG. 1 is a diagram showing the configuration of a mobile communication system according to the present invention.

[0023] According to Fig. 1, a terminal (User Equipment) 2 is accommodated in a mobile network core system via multiple access points (Access Points) 3 in a RAN (Radio Access Network). The multiple access points 3 are connected to one base station CPU. The terminal 2 communicates with one application server 6 via the mobile network core system.

[0024] Moreover, according to the mobile network core system of FIG. 1, a control device 1 serving as a control plane, and a plurality of gateways 4 and a proxy server 5 serving as a user plane are arranged. A terminal 2 simultaneously communicates with one application server 6 via multiple access points 3 and multiple gateways 4 and a proxy server 5 .

[0025] The terminal 2 can simultaneously connect wireless links to multiple access points 3 and simultaneously establish multiple sessions. Such a function pre-installed in the terminal 2 becomes a terminal-side end node for multiple sessions and is also called, for example, a "bulk TCP client." This function is activated when the user starts a large-volume communication with one application server 6.

[0026] The control device 1 is a group of network devices that are configured as a control plane by a plurality of functions and transmit and receive control signals for establishing communication and the like. The control device 1 is responsible for session management between the terminal 2 and the application server 6. Of course, it is not limited to this, and also centrally manages registration, connection, and mobility of terminals, and assigns IP (Internet Protocol) addresses to terminals. In particular, according to the present invention, the control device 1 controls the establishment of multiple sessions via multiple access points and gateways when a terminal communicates with one application server 6 .

[0027] The multiple gateways 4 relay between any multiple access points 3 and the proxy server 5 via a session. A session is specified by a combination of an access point 3 and a gateway 4. According to FIG. 1, the number of access points is 3 and the number of gateways is 4.

[0028] The proxy server 5 terminates multiple sessions established with the terminal 2, and establishes a TCP (Transmission Control Protocol) connection with the application server 6. Then, it transfers user data received from the terminal 2 via the multiple sessions to the application server 6, and transfers user data received from the application server 6 to the terminal 2 via the multiple sessions. The proxy server 5 serves as a mobile core side termination node for the multiple sessions established with the terminal 2, and is also called, for example, a "bulk TCP proxy."

[0029] 1, the total number of combinations (full mesh) of the multiple access points 3 to which the terminal 2 can connect and the multiple gateways 4 that can relay between the access points 3 and the proxy server 5 is 12. Multiple sessions are selected from these 12 combinations.

[0030] FIG. 2 is an explanatory diagram illustrating a session in the mobile communication system of FIG.

[0031] The terminal 2 transmits and receives user data to and from one application server 6 via a plurality of PDU (Protocol Data Unit) sessions. The PDU session is identified by an IP address assigned to the terminal 2. According to Figure 2, three PDU sessions #1 to #3 are established as follows. Terminal-AP#1-GW#1-Proxy server-Application server -AP#2-GW#2- -AP#2-GW#4- From the perspective of the access point 3, at least only the gateways 4 that are physically connected are candidate nodes.

[0032] FIG. 3 is a sequence diagram according to the present invention.

[0033] <First step> (S11) The terminal 2 is assumed to have acquired the IP address of the application server 6 in advance. For example, the IP address may be preset in an application pre-installed in the terminal 2. Also, for example, the terminal 2 may acquire the IP address of the application server 6 by accessing a Domain Name Server (DNS). The terminal 2 is assumed to have at least one PDU session established at all times when the terminal 2 is turned on or when airplane mode is turned off, and to be in a state where it can connect to the Internet.

[0034] The terminal 2 detects access point IDs (identifiers) and radio wave strengths from multiple access points that can be connected as RAN. Then, the terminal 2 transmits a "session establishment request" including those access point IDs to the control device 1 via one access point 3. This session establishment request is also called a "bulk PDU session establishment request." The session establishment request may include, for example, the following information: Application Server Address ·Desired communication speed Direction (upstream / downstream / both directions) List [connectable access point ID, connection status, signal strength]

[0035] Incidentally, multiple sessions simultaneously established from the terminal 2 are also referred to as "bulk PDU sessions." Also, communication from the terminal 2 via the bulk PDU sessions is also referred to as "bulk PDU communication."

[0036] (S12) The control device 1 determines the number of PDU sessions to be established and selects an arbitrary combination of access points 3 and gateways 4. The control device 1 selects all or some of the combinations (full mesh) of a plurality of access points 3 to which the terminal 2 can connect and a plurality of gateways 4 that can relay between the access points 3 and the proxy server 5. For example, according to Fig. 1 described above, between three access points 3 and four gateways 4, there are 12 full mesh session candidates.

[0037] (S13) The control device 1 transmits to the terminal 2 an “access point connection request” including a list of combinations of a plurality of access points 3 and a plurality of gateways 4.

[0038] (S14) The terminal 2 simultaneously connects wireless links to the multiple access points 3 described in the list included in the access point connection request.

[0039] (S15) Then, the terminal 2 returns an “access point connection response” to the control device 1.

[0040] (S16) In order to communicate with one application server 6, the terminal 2 establishes a session with the proxy server 5 via the access point 3 and the gateway 4 for each combination in the list. According to Fig. 3, similar to Fig. 2, three PDU sessions #1 to #3 are established as follows: Terminal-AP#1-GW#1-Proxy server-Application server -AP#2-GW#2- -AP#2-GW#4-

[0041] (S17) The control device 1 notifies the proxy server 5 of the application server address.

[0042] (S18) The proxy server 5 establishes a connection with the application server 6 based on the application server address requested by the terminal 2. This connection may be, for example, TCP.

[0043] <Second step> The terminal 2 branches one stream of packets into a plurality of sessions, and transmits each session to the proxy server 5 via the access point 3 and the gateway 4.

[0044] <Third step> The proxy server 5 integrates packets received from a plurality of gateways 4 via a plurality of sessions into one stream, and transfers the integrated single stream to the application server 6 via the established connection.

[0045] FIG. 4 is an explanatory diagram showing the selection of a session according to the load factor of an access point and a gateway.

[0046] The control device 1 selects the number of any combination of access points 3 and gateways 4 so as not to exceed the upper limit number of sessions per terminal (e.g., 15). The upper limit number of sessions may be set as a static value by an operator, or may be updated as a dynamic value according to the accommodation status of the access points 3 and / or gateways 4.

[0047] It is also assumed that the control device 1 constantly detects the load factors of the access points 3 and the gateways 4. The load factors can be recognized, for example, from the frequency of congestion or the percentage of available bandwidth.

[0048] (1) For any access point 3 and / or gateway 4, the access point 3 and / or gateway 4 whose processing load rate or communication error rate exceeds a predetermined threshold is excluded from the candidate nodes of the PDU session. The predetermined threshold may be set as a static value by an operator, or may be updated as a dynamic value according to the accommodation status of the access point 3 and / or gateway 4. In addition, as another embodiment, a combination of access points 3 and gateways 4 that does not include an access point 3 or gateway 4 whose processing load rate or communication error rate deviates from the average value by a predetermined rate or more may be selected.

[0049] (2) Next, calculate the number of full-mesh connections between the access point 3 of the candidate node and the gateway 4. If the number of full-mesh connections exceeds the upper limit of sessions per terminal, select PDU sessions in ascending order of the communication path with the lowest load factor.

[0050] (3) If the number of full meshes is less than the maximum number of sessions per terminal, a PDU session is established in full mesh.

[0051] According to FIG. 4, it is assumed that the load factors of the access points AP#1 to AP#3 are as follows. AP#1: Load factor 30% AP#2: Load factor 50% AP#3: Load factor 70% Average load factor=(30%+50%+70%) / 3=50% Also, assume that the deviation threshold from the average load factor is set to "+10%." In this case, AP#3, whose load factor exceeds 60% (=50%+10%), is excluded from the PDU session.

[0052] Also, according to FIG. 4, it is assumed that the load factors of the gateways GW#1 to GW#4 are as follows. GW#1: Load factor 30% GW#2: Load factor 50% GW#3: Load factor 70% GW#4: Load factor 40% Average load factor=(30%+50%+70%+40%) / 4=47.5% Also, assume that the deviation threshold from the average load factor is set to "+10%." In this case, GW#3, whose load factor exceeds 57.5% (=47.5% + 10%), is excluded from the PDU session.

[0053] As shown in Figure 4, even in a wireless communication environment where random packet loss is likely to occur, it is possible to realize TCP-type (AIMD-type delivery data loss avoidance and order maintenance) multipath communication while suppressing the amount of information managed by the gateway in the mobile network core system and reducing the relay processing load as much as possible.

[0054] <Another embodiment in which a stream is branched into multiple substreams> When high-volume communication is performed between the terminal 2 and the application server 6, the data flow increases. This places a heavy load on the gateway 4 in the user plane of the mobile network core system. The gateway 4 manages a flow table for identifying data flows, and the size of this flow table increases. If the number of data flows that the gateway 4 must manage and identify increases, a heavy load is placed on the flow table search process during relay. Therefore, as another embodiment, a sequence is applied in which a stream is branched into multiple sub-streams and a PDU session with the lightest possible load is passed through.

[0055] FIG. 5 is an explanatory diagram showing the relationship between streams and substreams.

[0056] 5, one stream to be transmitted by terminal 2 is made up of packets 1 to 5. The stream is identified by the source port number of terminal 2. Terminal 2 generates multiple sub-streams from one stream. Here, one stream is composed of n substreams with redundancy of n. The multiple substreams are copies of the packet sequence of one stream. The substreams are identified by a combination of the IP address of the terminal and the source port number.

[0057] According to FIG. 5, one stream is composed of two substreams with a redundancy of two. Terminal 2 copies one stream into two substreams and transmits each substream via a PDU session to proxy server 5. The two substreams copied from the same stream are each branched into a different PDU session. This separates the communication paths, and makes it possible to reduce the correlation between the timing of loss occurrence between the substreams.

[0058] Terminal 2 allocates large volumes of traffic for one application to multiple streams. It also manages the window size for each stream. For example, it may allocate the traffic of the application in order of the stream with the largest available window size. Then, multiple substreams are generated from each stream.

[0059] When the proxy server 5, which is the receiver of the substreams, receives a packet with a given sequence number from one of the different substreams for the first time, it considers that reception of the packet with that sequence number is complete. At this time, it operates to increase the window size for one stream linked to that substream. This reduces the apparent packet loss rate, realizes high-volume communication with a smaller number of data flows, and reduces the processing load of communication devices such as the gateway 4.

[0060] In the next embodiment, the problem arises as to how to allocate multiple sub-streams generated from one stream to multiple established PDU sessions.

[0061] FIG. 6 is an explanatory diagram showing a combination of a plurality of substreams.

[0062] According to FIG. 6, three patterns are shown as follows for arranging two substreams with redundancy of 2 for three PDU sessions. (First arrangement pattern) Substream#1: AP#1-GW#1 Substream#2: AP#2-GW#2 (Second arrangement pattern) Substream#1: AP#1-GW#1 Substream#2: AP#2-GW#4 (Third arrangement pattern) Substream#1: AP#2-GW#2 Substream#2: AP#2-GW#4 As shown in FIG. 4, it is assumed that AP#3 and GW#3, whose load rates are higher than the deviation rate, have already been excluded.

[0063] In this way, terminal 2 transmits multiple sub-streams #1 and #2 to PDU sessions with different combinations of access points 3 and gateways 4, respectively. When the proxy server 5 receives a packet with a given sequence number from either of the different sub-streams #1 and #2 for the first time, it considers that reception of the packet with that sequence number has been completed.

[0064] It is also assumed that the control device 1 measures the transmission speed for each PDU session consisting of a combination of the access point 3 and the gateway 4. (First arrangement pattern): Sum of transmission speeds Sub-stream #1: AP#1-GW#1 :100Mbps :150Mbps Sub-stream #2: AP#2-GW#2: 50Mbps (Second arrangement pattern) Sub-stream #1: AP#1-GW#1 :100Mbps :110Mbps Sub-stream #2: AP#2-GW#4: 10Mbps (Third arrangement pattern) Sub-stream #1: AP#2-GW#2 :50Mbps :60Mbps Sub-stream #2: AP#2-GW#4: 10Mbps It should be noted that the transmission speed is an "expected speed value" and is constantly measured and updated by the control device 1. It is also assumed that the sum of the transmission rates of multiple substreams is proportional to the expected rate per stream.

[0065] In addition, if the substream redundancy n (= 2) is smaller than the number of sessions k (= 3) (k>n), k C nAmong the combinations, the combination with the highest sum of transmission rates in multiple sessions per stream is selected. According to Fig. 6, the first allocation pattern with the highest sum of transmission rates is selected. Of course, it is not limited to the transmission speed, but may be the delay time or the packet loss rate.

[0066] The substream arrangement determined as shown in FIG. stream Port number ·Redundancy (2) PDU Session List Substream#1: AP#1-GW#1 Substream#2: AP#2-GW#2

[0067] As described above in detail, the communication method according to the present invention and System To This makes it possible to establish multiple sessions via multiple access points and gateways, which is suitable for realizing large-volume communication between a terminal and one application server.

[0068] Furthermore, as a result, for example, "it will be possible to reduce the relay processing load in the mobile network core system even when a terminal communicates with an application server with high volumes of data," which will contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs) "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0069] Regarding the various embodiments of the present invention described above, various changes, modifications, and omissions within the scope of the technical idea and perspective of the present invention can be easily made by those skilled in the art. The above description is merely an example and is not intended to be restrictive in any way. The present invention is limited only by the scope of the claims and their equivalents. [Explanation of symbols]

[0070] 1 Control device 2. Terminal 3. Access Points 4. Gateway 5. Proxy Server 6 Application Server

Claims

1. A communication method in which a terminal communicates with an application server using a control device via a plurality of access points, a plurality of gateways, and a proxy server, comprising: A terminal transmits a session establishment request including identifiers of a plurality of connectable access points to a control device in order to communicate with one application server; The control device selects an arbitrary combination of an access point and a gateway, and transmits an access point connection request including a list of the combination to the terminal; a first step in which the terminal establishes a session with the proxy server via the access point and the gateway for each combination; a second step in which the terminal branches one stream of packets into a plurality of sessions and transmits each session to the proxy server via the access point and the gateway; a third step in which the proxy server aggregates packets received from the multiple gateways via the multiple sessions into one stream and forwards the aggregated single stream to the application server; A communication method comprising:

2. Regarding the first step, The session establishment request sent by the terminal further includes an application server address; The control device notifies the proxy server of the application server address, The proxy server establishes a connection with the application server based on the application server address; In the third step, the proxy server forwards the integrated stream to the application server via the established connection.

2. The communication method according to claim 1 .

3. Regarding the first step, The control device selects all or a part of combinations from among all combinations (full mesh) of a plurality of access points to which the terminal can be connected and a plurality of gateways that can relay between the access points and the proxy server.

3. The communication method according to claim 1 or 2.

4. The number of any combination of access points and gateways is selected so as not to exceed the maximum number of sessions per device.

4. The communication method according to claim 3.

5. Among combinations of access points and gateways, a combination is selected that does not include an access point or gateway whose processing load rate or communication error rate exceeds a predetermined threshold.

5. The communication method according to claim 3 or 4.

6. Among the combinations of access points and gateways, a combination is selected that does not include an access point or gateway whose processing load rate or communication error rate deviates from the average value by a predetermined rate or more.

6. The communication method according to claim 5.

7. One stream is composed of multiple substreams with redundancy n, The multiple substreams are copies of a packet sequence of one stream, Each of the multiple sub-streams is transmitted to a session having a different combination of the access point and the gateway; When the proxy server receives a packet with a given sequence number from one of the different substreams for the first time, it considers the packet with that sequence number to be completely received.

7. A communication method according to claim 1, wherein the first and second communication paths are connected to each other.

8. The transmission speed is measured for each session consisting of a combination of an access point and a gateway. When the substream redundancy n is smaller than the number of sessions k (k>n), k C n Among the possible combinations, the combination with the highest sum of the transmission rates of multiple sessions per stream is selected.

8. The communication method according to claim 7.

9. A system in which a terminal is configured to communicate with an application server via a plurality of access points and a plurality of gateways and a proxy server using a control device, A terminal transmits a session establishment request including identifiers of a plurality of connectable access points to a control device in order to communicate with one application server; The control device selects an arbitrary combination of an access point and a gateway, and transmits an access point connection request including a list of the combination to the terminal; the terminal establishes a session with the proxy server via the access point and the gateway for each combination; A terminal establishes a session with a proxy server for each combination of an access point and a gateway in order to communicate with one application server; A terminal branches one stream of packets into a plurality of sessions and transmits each session to a proxy server via an access point and a gateway; The proxy server combines packets received from multiple gateways via multiple sessions into one stream and forwards the combined stream to the application server. A system characterized by:

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