Base station system, unit and control device of the base station system, method executed by the base station system, and program

Abstract

To provide a user device with a service provided by a network slice that the user device selected, in a multi-connection base station system.SOLUTION: A base station system comprises: a first unit that has a function to process a wireless signal; and a plurality of second units each having a function of a higher layer than the function of the first unit. One of the second units is an initial unit that performs random access to user equipment. The initial unit includes: setting means that, upon receiving from the user equipment a communication request including identification information indicating a first network slice, sets a communication connection with the user equipment; determination means that determines a providing unit, among the plurality of second units, the second unit providing the first network slice; and processing means that, if the initial unit is different from the providing unit, executes processing to hand over the communication connection to the providing unit.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a base station system composed of a plurality of units that can be distributed at different geographical locations.

Background Art

[0002] Conventionally, a base station device of a mobile communication network (hereinafter simply referred to as a base station) has been installed at an antenna site where an antenna is installed, and various processes for transmitting user data as a radio signal have been performed within one device. On the other hand, in recent years, the functions of the base station have been divided, and devices (units) that realize the divided functions have been arranged at different sites. Hereinafter, a base station composed of a plurality of units that can be arranged at different geographical locations is referred to as a base station system. For example, the 3rd Generation Partnership Project (3GPP) has proposed dividing the base station functions into a Central Unit (CU), a Distributed Unit (DU), and a Radio Unit (RU). For example, the CU performs processes related to the SDAP layer and the PDCP layer, the DU performs processes related to the RLC layer, the MAC layer, and a part of the physical layer, and the RU performs the remaining processes of the physical layer including radio signal transmission and reception processes.

[0003] Patent Document 1 discloses a base station system in which a plurality of sets of DUs and CUs are connected to one RU. In the following description, the base station system in which a plurality of sets of DUs and CUs disclosed in Patent Document 1 are connected to one RU is referred to as a "multi-connected base station system". According to Patent Document 1, a certain set of DUs is arranged at the antenna site, and the CU is arranged at the data center. Also, a certain set of DUs is arranged at the antenna site, and the CU is arranged at the local accommodation office. Note that the antenna site is the site where the RU is arranged, and the local accommodation office is the site where the communication delay with the antenna site is smaller than that of the data center. Furthermore, according to Patent Document 1, a certain set of DUs and CUs are both arranged at the local accommodation office. Note that these arrangement patterns are examples, and the arrangement of the set of CUs and DUs is determined according to, for example, the network slice provided by the set.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] FIG. 1 shows the base station system disclosed in Patent Document 1. According to FIG. 1, sets 20 of DUs and CUs are each connected to one RU 10. Each set 20 is connected to the core network 30. In the following description, when distinguishing the three sets 20, they are denoted as set #1, set #2, and set #3. According to FIG. 1, set #1 provides network slice #1-1 (hereinafter, the network slice is simply denoted as a slice), set #2 provides slices #2-1 and #2-2, and set #3 provides slices #3-1 and #3-2. Note that the sites where the DUs and CUs of each of set #1, set #2, and set #3 are arranged are determined according to, for example, the slice provided by set 20.

[0006] In the configuration of FIG. 1, when the application of the user equipment (UE) 40 uses slice #3-2, the UE 40 must execute a random access procedure with Set #3 and establish a protocol data unit (PDU) session via Set #3. However, the procedure for the UE 40 to select a set from among a plurality of Sets 20 connected to one RU to execute the random access procedure is not defined. That is, the UE 40 cannot establish a PDU session via Set #3 that provides the slice #3-2 it wants to use, and thus cannot receive the service provided by slice #3-2.

[0007] Note that, instead of dividing the functions of the base station apparatus into an RU, a DU, and a CU, when the functions of the base station apparatus are divided into a first unit having a function of processing radio signals and a second unit having a function of a higher layer than the function of the first unit, and a plurality of second units are connected to one first unit, a similar problem may occur. That is, the UE 40 cannot execute random access by designating the second unit that provides the slice that the UE 40 wants to use, that is, the slice selected by the UE 40, and thus cannot receive the service provided by the slice.

[0008] The present invention provides a technique for causing a user equipment to receive a service provided by a network slice selected by the user equipment in a multi-connection base station system.

Means for Solving the Problem

[0009] According to one aspect of the present invention, a base station system includes a first unit having a function of processing radio signals, and a plurality of second units having functions of higher layers than the functions of the first unit. Each of the plurality of second units provides one or more network slices. One of the plurality of second units is an initial unit that executes random access with a user device. When the initial unit receives a communication request including identification information indicating a first network slice from the user device, the initial unit includes a setting means for setting a communication connection with the user device, a determination means for determining a providing unit that provides the first network slice among the plurality of second units, and when the initial unit and the providing unit are different, a processing means for executing a process of handing over the communication connection to the providing unit. , each of the plurality of second units includes a third unit and a fourth unit having a function of a higher layer than the function of the third unit, the first unit is a radio unit (RU), the third unit is a distributed unit (DU), and the fourth unit is a central unit (CU). 。

Advantages of the Invention

[0010] According to the present invention, in a multi-connection base station system, a user device can be made to receive a service provided by a network slice selected by the user device.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and not all combinations of the features described in the embodiments are essential for the invention. Two or more of the features described in the embodiments may be arbitrarily combined. Also, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0013] FIG. 2 is a configuration diagram of a radio access network (RAN) including a base station system 100 according to this embodiment. For the same configuration as in FIG. 1, detailed description is omitted. Also in FIG. 2, the base station system 100 has one RU 10 and three sets 20 connected to this RU 10. Note that one set 20 includes one DU and one CU. The DU and the CU can each be divided into a user plane function (UPF) that transfers data and a control plane function (CPF) that transmits and receives control signals to and from other devices to control the UPF. The set 20 shown in FIG. 2 includes both the UPF and the CPF of the DU and the CU.

[0014] Similar to FIG. 1, set #1 provides slice #1-1, set #2 provides slices #2-1 and #2-2, and set #3 provides slices #3-1 and #3-2. Note that the number of slices provided by each set 20 can be any number of one or more. Also, in FIG. 2, the number of sets 20 is set to 3, but the number of sets 20 can be any number of two or more. That is, the present invention can be applied to the configuration of the base station system 100 in which a plurality of sets 20 are connected to one RU. Note that the radio resources in the radio section are allocated to each set 20. Note that the allocation of radio resources to each set 20 may be static or dynamic.

[0015] In FIG. 2, the control device 50 is a control device of the RAN. The control device 50 can be, for example, a Near-Real-Time RAN Intelligence Controller (Near-RT RIC) specified by the Open RAN (O-RAN) Alliance.

[0016] The control device 50 holds the determination information shown in FIG. 3. The determination information is information for determining the slices provided by each set 20. Note that S-NSSAI (Single Network Slice Selection Assistance Information) is identification information for identifying and discriminating slices. In this example, the S-NSSAI of slice #m-k is denoted as #m-k. From the determination information shown in FIG. 3, it can be seen that set #1 provides slice #1-1, set #2 provides slices #2-1 and #2-2, and set #3 provides slices #3-1 and #3-2. For example, each set 20 may be configured to notify the control device 50 of the S-NSSAI of the slices it provides, together with the identifier of that set 20, after startup. Note that the identifier of set 20 can be a combination of the identifiers of the DU and CU of that set 20.

[0017] FIG. 4 is a sequence diagram according to this embodiment. At S1, an application is launched in UE 40. Note that this application is assumed to utilize slice #3-2. At S2, UE 40 executes random access. In this embodiment, the radio resources for random access are allocated only to set #1, and thus, the base station system 100 is configured such that the set 20 to which UE 40 performs random access is always set #1. For example, the random access channel, which is dedicated for random access, is allocated only to set #1, and the base station system 100 may be configured such that the signal transmitted by UE 40 on the random access channel is always transferred to set #1. Note that the order of S1 and S2 may be reversed.

[0018] When the random access is completed, the UE 40 transmits, in S3, a request message for requesting the establishment of a PDU session to Set #1 where the random access was performed. The request message includes identification information for identifying the slice to be used, in this example, S-NSSAI #3-2. The request message is transferred from Set #1 to the access and mobility management function (AMF) of the core network 30, whereby a PDU session from the UE 40 to the connection point between the core network 30 and an external network (e.g., the Internet) is established in S4. This PDU session includes a sub-session between the UE 40 and Set #1 and one or more sub-sessions from Set #1 to the external network. Note that each sub-session can also be referred to as a PDU session.

[0019] When the PDU session is established, the CPF of the CU in Set #1 transmits, in S5, a report message to the control device 50. The report message includes the identification information of the slice included in the request message, that is, S-NSSAI #3-2. The report message can use the Report function defined in, for example, Section 8.2 of O-RAN.WG3.E2SM-RC-v01.00, RAN Parameters for Report Service.

[0020] When the control device 50 receives a report message, it refers to the determination information and determines the set 20 that provides the slice indicated by the slice identification information included in the report message. From FIG. 3, the slice #3-2 corresponding to S-NSSAI#3-2 is provided by the set #3. In S6, the control device 50 transmits a Control message to the set #1 as a response to the report message. The control message includes information indicating the determined set 20, in this example, the set #3. Note that the control message can be implemented by modifying the Control function defined in, for example, Control Service Style3:Connected Mode Mobility in Section 7.6.4 of O-RAN.WG3.E2SM-RC-v01.00.

[0021] When the CPF of the CU of the set #1 receives the control message, it starts the process of handing over the PDU session set in S4 to the set #3 included in the control message. This process can use the existing handover sequence. As a result, the PDU session is changed to be via the set #3.

[0022] In this embodiment, the functions of the base station apparatus are divided into three parts: RU, DU, and CU, and a set of one DU and one CU is defined as set 20. However, the present invention can also be applied to a configuration in which the functions of the base station apparatus are divided into at least two units, a first unit and a second unit, and a plurality of second units are connected to one first unit. The first unit is, for example, an RU and has at least a function of processing radio signals. The second unit has functions of a higher layer than the functions of the first unit. The second unit also has a function of performing random access. Note that the second unit can be further divided into two or more units (or sub-units). The above embodiment is an example in which the second unit is divided into two parts, DU and CU, but the number of divisions can also be three or more. The first unit is arranged at the antenna site, and the plurality of second units connected to the first unit can be arranged at various sites. Further, when the second unit is divided into a plurality of sub-units, the plurality of sub-units constituting one second unit can be arranged at various sites.

[0023] In summary, the base station system 100 of this embodiment includes a first unit having a function of processing radio signals and a plurality of second units having functions of a higher layer than the functions of the first unit. Each of the plurality of second units provides one or more network slices. One of the plurality of second units performs random access with the UE 40 and is hereinafter also referred to as the initial unit. This can be achieved by allocating radio resources used only for random access of the radio signals transmitted and received by the first unit, that is, the random access channel, only to the initial unit. Regardless of the slice to be used, the UE 40 executes random access with the initial unit. When the random access is completed, the UE 40 requests a PDU session from the initial unit and establishes a PDU session with the initial unit. At this time, the UE 40 transmits identification information of the slice for which use is requested to the initial unit.

[0024] When the initial unit establishes a PDU session, it notifies the RAN control device 50 of the identification information of the slice requested by the UE 40 to use, and obtains information indicating the second unit that provides the slice from the control device 50. When the second unit (providing unit) that provides the slice is another second unit different from the initial unit, the initial unit starts a procedure to hand over the established PDU session to the other second unit. With this configuration, in the "multi-connection base station system", the UE 40 can be made to receive the service provided by the slice selected by the UE 40.

[0025] Note that the processing after S5 in FIG. 5 can be configured to be executed only when the initial unit does not provide the slice corresponding to the slice information included in the request message. That is, in this example, when the slice information included in the request message is S-NSSAI#1-1, the set #1 which is the initial unit can also be configured not to transmit the report message to the control device 50.

[0026] In the above embodiment, it is described as a PDU session according to the terms of 3GPP's New Radio (NR) or 5G, but the PDU session corresponds to a bearer in Long-Term Evolution or 4G. Here, the PDU session and the bearer are communication connections established in the mobile communication network for transferring packets between the UE and an external network of the mobile communication network such as the Internet. Therefore, the PDU session and the bearer can also be generically referred to as communication connections.

[0027] In addition, the present invention can also be applied when applying network virtualization technology to the base station system 100. That is, the second unit can be a virtual unit realized by a group of computers arranged at each site.

[0028] Figure 5 is a configuration diagram of the initial unit. The first communication unit 204 is a communication interface with RU10 and other second units, and the second communication unit 205 is a communication interface with the core network 30 and the control device 50. Note that the communication with RU10, other second units, the core network 30, and the control device 50 can also be configured to use the same communication interface. Also, the communication with RU10, other second units, the core network 30, and the control device 50 can be configured to use individual communication interfaces. That is, the relationship between the communication interface and the communication partner is arbitrary.

[0029] The random access execution unit 200 executes random access with the UE40 via the first communication unit 204. The connection setting unit 201 sets up a communication connection in response to a communication request from the UE40. Note that the communication request corresponds to the PDU session request in S3 of FIG. 3, and the communication connection corresponds to the PDU session.

[0030] The determination unit 203 determines a providing unit, which is a second unit that provides the slice indicated by the identification information, based on the identification information of the slice included in the communication request. For example, as shown in FIG. 4, the determination unit 203 notifies the control device 50 of the identification information of the slice included in the communication request via the second communication unit 205, and as a response, obtains information indicating the providing unit from the control device 50 to determine the providing unit.

[0031] Note that the determination information shown in FIG. 3 can also be stored in a storage device (not shown) of the initial unit. In this case, the initial unit can determine the providing unit based on the determination information stored in the storage device and the identification information of the slice included in the communication request. Note that the initial unit can obtain the determination information from the control device 50. Alternatively, a second unit other than the initial unit can notify the initial unit of the identifier of the slice it provides, so that the initial unit can obtain the determination information.

[0032] When the providing unit is not the initial unit, the handover execution unit 202 executes a process for causing the communication connection to be handed over to the providing unit via the first communication unit 204.

[0033] FIG. 6 is a configuration diagram of the control device 50. The communication unit 504 performs communication processing with the base station system 100. The determination information storage unit 500 stores determination information. When the communication unit 504 receives a message including identification information indicating a network slice from the initial unit, the communication unit 504 outputs the identification information to the determination unit 501. The determination unit 501 determines a providing unit that provides the network slice indicated by the identification information based on the identification information and the determination information, and outputs the determination result to the communication unit 504. The communication unit 504 notifies the initial unit of the providing unit.

[0034] Furthermore, the control device 50 and the base station system 100 according to the present disclosure can be realized by a computer program that, when executed by the one or more processors of a device (for example, a computer) having the one or more processors, causes the device to operate as the control device 50 and the base station system 100 described above. Note that the computer program is stored in a computer-readable storage medium such as one or more memories of the device, for example.

[0035] The invention is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the invention.

[0036] With the above configuration, in a multi-configuration, it is possible to cause the user device to receive a service provided by the network slice selected by the user device. Therefore, it is possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

Description of Reference Numerals

[0037] 10: RU, 20: Set, 30: Core Network, 40: User Equipment, 50: Control Equipment

Claims

1. A base station system comprising a first unit having a function of processing a radio signal, and a plurality of second units having functions of a higher layer than the function of the first unit, wherein: each of the plurality of second units provides one or more network slices; one of the plurality of second units is an initial unit that executes random access with a user equipment; the initial unit: when receiving a communication request including identification information indicating a first network slice from the user equipment, a setting means for setting a communication connection with the user equipment; a determination means for determining a providing unit that provides the first network slice among the plurality of second units; when the initial unit and the providing unit are different, a processing means for executing a process of handing over the communication connection to the providing unit; and is provided with; each of the plurality of second units has a third unit and a fourth unit having a function of a higher layer than the function of the third unit; the first unit is a radio unit (RU), the third unit is a distributed unit (DU), and the fourth unit is a central unit (CU), the base station system.

2. The base station system according to claim 1, wherein a radio resource dedicated to the random access among the radio signals processed by the first unit is allocated only to the initial unit.

3. further comprising a holding means for holding determination information indicating network slices provided by each of the plurality of second units; the determination means determines the providing unit based on the identification information indicating the first network slice and the determination information, the base station system according to claim 1 or 2.

4. The base station system according to claim 3, wherein a second unit different from the initial unit among the plurality of second units is configured to notify the initial unit of the identification information of the network slice being provided.

5. further comprising a communication means for communicating with a control device that holds determination information indicating network slices provided by each of the plurality of second units; The base station system according to claim 1 or 2, wherein the determination means notifies the control device of the identification information and acquires information indicating the providing unit from the control device to determine the providing unit.

6. The base station system according to claim 5, wherein the plurality of second units are configured to notify the control device of the identification information of the network slice being provided.

7. In a radio unit having a function of processing radio signals, a plurality of units each providing one or more network slices are connected, and one of the plurality of units is a unit that executes random access with a user device. The unit that executes random access in the base station system, a setting means for setting a communication connection with the user device when receiving a communication request including identification information indicating a first network slice from the user device; a determination means for determining a providing unit that provides the first network slice among the plurality of units; a processing means for executing a process of handing over the communication connection to the providing unit when the providing unit is another unit among the plurality of units; comprising each of the plurality of units has a distributed unit (DU) and a central unit (CU) having a function of a layer higher than the function of the distributed unit.

8. A control device for a base station system having a first unit having a function of processing radio signals and a plurality of second units having a function of a layer higher than the function of the first unit, each of the plurality of second units provides one or more network slices, one of the plurality of second units is an initial unit that executes random access with a user device, the control device a holding means for holding determination information indicating the network slices provided by each of the plurality of second units; a receiving means for receiving a message including identification information indicating a first network slice from the initial unit; a determination means for determining a providing unit that provides the first network slice among the plurality of second units based on the identification information and the determination information; a notification means for notifying the initial unit of the providing unit; comprising Each of the plurality of second units includes a third unit and a fourth unit having a function of a higher layer than the function of the third unit. The control device, wherein the first unit is a radio unit (RU), the third unit is a distributed unit (DU), and the fourth unit is a central unit (CU). **Claim 9** A program that, when executed by the one or more processors of a device having one or more processors, causes the device to function as the control device according to claim 8. **Claim 10** A method executed by a base station system including a first unit having a function of processing a radio signal and a plurality of second units having functions of a higher layer than the function of the first unit, wherein each of the plurality of second units provides one or more network slices, one of the plurality of second units is an initial unit that executes random access with a user equipment, the method including: setting up a communication connection between the initial unit and the user equipment in response to receiving a communication request including identification information indicating a first network slice from the user equipment; determining a providing unit that provides the first network slice among the plurality of second units; when the initial unit and the providing unit are different, handing over the communication connection to the providing unit; and each of the plurality of second units includes a third unit and a fourth unit having a function of a higher layer than the function of the third unit. The method, wherein the first unit is a radio unit (RU), the third unit is a distributed unit (DU), and the fourth unit is a central unit (CU). **Claim 11** A program that, when executed by one or more processors, causes the one or more processors to execute the method according to claim 10.

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