JP7252854B2 - Control device, control method and program - Google Patents

Description

The present invention relates to a control device and control method for a base station system to which network slicing is applied, and a program for the control device.

In the fifth generation (5G) mobile communication system, the service types are large capacity (eMBB: enhanced Mobile BroadBand), ultra-low latency (URLLC: Ultra-Reliable and Low Latency Communications), and multi-connection (mMTC: massive Machine Type Communications). It is roughly divided into three types, each with different service requirements. In order to economically and flexibly provide services with different requirements, network slicing is being studied.

In addition, in 5G, the first version of which has been formulated as 3GPP Release 15, a base station is configured with a logical node called DU (Distributed Unit) and a logical node called CU (Central Unit), and DU and CU It is adopted to divide the functions of the base stations between them. DU includes base station functions (RF (Radio Frequency layer), PHY (Physical layer), MAC (Media Access Control layer), RLC (Radio Link Control layer), PDCP (Packet Data Convergence Protocol layer)) Among them, the functions of the lower layer are arranged, and the functions of other upper layers are arranged in the CU. In addition to the CU and DU, a radio unit (RU: Radio Unit) having functions such as RF and PHY can also be provided.

When the above-described network slicing is applied to a base station system in which functions are divided into DUs and CUs in this way, a scheduler that schedules radio resources for radio terminals in each slice corresponds to each slice. Placed in DU. In a configuration in which one RU is shared by multiple DUs, multiple schedulers perform scheduling using common radio resources within the same base station area, so radio resource isolation is achieved between slices. There is a need. In addition, when allocating radio resources used for scheduling for each slice to each slice (each scheduler), the level of satisfaction with the SLA (service level agreement) of each slice is enhanced (the service quality provided by each slice is enhanced). is required.

Non-Patent Document 1 proposes a technique for allocating radio resources for scheduling to each slice based on a predetermined allocation ratio so as to ensure isolation between slices when network slicing is applied. ing. In addition, Non-Patent Document 2 proposes a technique for allocating radio resources for scheduling to each slice so as to increase the satisfaction of the SLA of each slice when network slicing is applied.

A. Ksentini and N. Nikaein "Toward Enforcing Network Slicing on RAN: Flexibility and Resources Abstraction," IEEE Communications Magazine, Jun. 2017, vol. 55, issue 6, pp. 102-108. B. Khodapanah, A. Awada, I. Viering, D. Oehmann, Meryem Simsek, and G. P. Fettweis, "Fulfillment of Service Level Agreements via Slice-Aware Radio Resource Management in 5G Networks," 2018 IEEE 87th Vehicular Technology Conference (VTC Spring ), pp. 1-6, Jun. 2018.

However, in the conventional technology described above, it is not possible to distribute (assign) radio resources for scheduling to each slice so as to improve the satisfaction of the SLA while ensuring isolation. For example, in Non-Patent Document 2, in an attempt to uniformly improve the satisfaction level of SLA for a plurality of slices, by allocating too much radio resources to a slice in which a radio terminal having a poor radio environment exists, A situation may arise in which radio resources to be allocated are insufficient. In this case, isolation between slices cannot be ensured.

Also, when network slicing is applied to a base station system in which functions are divided into DUs and CUs, there is a possibility that multiple schedulers corresponding to different slices will be arranged at different locations (sites). be. However, the conventional technology described above does not assume that multiple schedulers are arranged at different locations, and cannot be applied in such a case.

The present invention has been made in view of the above problems. The present invention provides a technique for allocating radio resources to each slice in a base station system to which network slicing is applied so as to improve the quality of service provided by each slice while ensuring isolation between slices. It is intended to

A control device according to an aspect of the present invention is a control device that allocates, to each of a plurality of slices, radio resources used for scheduling for each slice, and according to a predetermined allocation ratio, A determination means for determining a provisional allocation amount of radio resources for each slice, and a predicted communication capacity obtained based on the amount of radio resources allocated to the slice and the communication quality of the slice for each slice. a first allocation means for allocating radio resources to the slice with the temporary allocation amount as an upper limit until a target value determined for the slice is satisfied; 1. Allocating surplus radio resources that were not allocated to slices satisfying the target value to one or more slices for which the amount of radio resources allocated by the allocating means has reached the upper limit; and allocation means.

According to the present invention, in a base station system to which network slicing is applied, it is possible to allocate radio resources to each slice so as to improve the service quality provided by each slice while ensuring isolation between slices. be possible.

FIG. 3 is a diagram showing a functional configuration example of CU, DU and RU in a base station system; The figure which shows the basic structural example of a base station system. The figure which shows the structural example of a base station system. FIG. 2 is a block diagram showing a hardware configuration example of a RAN controller; FIG. 2 is a block diagram showing a functional configuration example of a RAN controller; FIG. 4 is a diagram showing an example of timing of allocating radio resources to a plurality of slices; FIG. 4 is a diagram showing an example of an AMC (Adaptive Modulation and Coding) mapping table for obtaining predicted throughput; FIG. 10 is a diagram showing an example of radio resource allocation results by the first and second allocation processes;

Exemplary embodiments of the invention will now be described with reference to the drawings. Note that, in each drawing below, constituent elements that are not necessary for the description of the embodiment are omitted from the drawing.

[First embodiment]
<Functional division of base station>
A base station (base station system) generally has a plurality of functions (RF, . be.

FIG. 1 is a diagram showing an example of a configuration in which multiple functions of different layers of a base station are divided into CUs, DUs, and RUs. As shown in FIG. 1, in this embodiment, in addition to CU and DU, RUs having functions such as RF and PHY are provided. The base station (base station system) in FIG. 1 is composed of CU10, DU20, and RU30. and RU30.

The DU 20 has at least a scheduling function of allocating radio resources to radio terminals, among the functions of the base station. The CU 10 has, among the functions of the base station, higher layer functions than the functions of the connected DU 20 . Further, the RU 30 has at least an RF function corresponding to a radio transmission/reception function among the base station functions.

In the configuration example of FIG. 1, the DU20 has not only the High MAC function corresponding to the scheduling function, but also the RLC and Low MAC functions, and the CU10 is a higher layer function than the function of the DU20. It has SDAP (Service Data Adaptation Protocol layer)/RRC (Radio Resource Control layer) and PDCP functions. Further, the RU 30 has not only an RF function corresponding to a radio wave transmission/reception function, but also a PHY function. Note that only some functions of the PHY may be implemented in the RU 30 and the remaining functions of the PHY may be implemented in the DU 20.

Hereinafter, the configuration and operation of the base station system according to this embodiment and the control of the base station system will be specifically described using the functional configuration shown in FIG. 1 as an example.

<Configuration of base station system>
FIG. 2 is a diagram showing a basic configuration example of a base station system in which slices 1 to 3 corresponding to mMTC, URLLC, and eMBB are generated as service types. The CU 10 and DU 20 are controlled and managed by a RAN (radio access network) controller 40, and each slice is generated by the RAN controller 40. FIG.

The base station system is composed of a plurality of CUs 10 (10a, 10b, 10c), a plurality of DUs 20 (20a, 20b, 20c), and one RU 30. CU10a and DU20a correspond to slice 1, CU10b and DU20b correspond to slice 2, and CU10c and DU20c correspond to slice 3. In this way, the multiple CUs 10 correspond to different slices, respectively, and the same applies to the multiple DUs 20 corresponding to the multiple CUs 10 . Note that each of the plurality of CUs 10 may correspond to one or more slices. Also, each of the plurality of DUs 20 may correspond to one or more slices.

The DU 20 has at least a radio resource scheduling function (for example, a High MAC function) among base station functions. The DUs 20 are each located at the antenna site or located between (the local station of) the antenna site and the data center.

Each CU 10 is arranged between one different DU of the DU 20 and the core network, and among the functions of the base station, the functions of the higher layer than the functions of the connected one DU (for example, SDAP/RRC and PDCP functions). In the example of FIG. 2, the CUs 10a, 10b, 10c are connected to one different DU 20a, 20b, 20c, respectively.

A single RU 30 has at least a radio wave transmission/reception function (for example, an RF function) among the base station functions. The RU 30 is placed at an antenna site and connected to multiple DUs 20 . Thereby, a plurality of slices 1 to 3 provided via a plurality of DUs 20 are provided within the same cell formed by the RU 30 concerned.

Thus, the base station system of the present embodiment is configured with CU10 and DU20 corresponding to slices 1 to 3, respectively, and a single RU30 connected to a plurality of DU20 and arranged at an antenna site. ing. That is, the base station system has a configuration in which multiple DUs and CUs are connected to a single RU (that is, multiple DUs and CUs share an RU) without providing an RU for each slice. have. This allows a single RU to accommodate multiple services (slices).

In this embodiment, the core network or RAN is provided with a RAN controller 40, which is a control device that controls the functions of the RAN. The RAN controller 40 is communicably connected to the base station system on the RAN. The RAN controller 40 sets (generates) slices 1 to 3 corresponding to service requirements for multiple CUs 10 (10a, 10b, 10c) and multiple DUs 20 (20a, 20b, 20c) on the RAN. Note that, in the present embodiment, the RAN controller 40 functions as an example of a control device that allocates radio resources used for scheduling for each slice to each of a plurality of slices.

In the configuration example of FIG. 2, a 5G network configuration is assumed as an example, and a 5GC CPF (5GC Control Plane Function) 60 is a control processing function group of the 5G core network. A 5GC UPF (5G Core User Plane Function) 50 (50a, 50b, 50c) is a data processing function group of the 5G core network, and is provided for each slice. The 5GC UPF 50a corresponds to slice 1, the 5GC UPF 50b to slice 2, and the 5GC UPF 50c to slice 3.

In the configuration example of FIG. 2, the arrangement of the corresponding CU10 and DU20 differs depending on the slice (service). Depending on the placement of the CU 10 and DU 20, the performance of inter-base station cooperation (inter-cell cooperation), the amount of delay given to applications, the network utilization efficiency, etc., differ. Therefore, in the configuration example of FIG. 2, the CU 10 and DU 20 are arranged appropriately for each slice (service).

For slice 1 (mMTC slice), CU 10a is located at the data center where the core network is located, and DU 20a is located at the antenna site. This is to enable efficient utilization of data center computing resources due to statistical multiplexing effects.

For slice 2 (URLLC slice), CU 10b is located at the local station and DU 20b is located at the antenna site. This makes it possible to introduce MEC (Multi-Access Edge Computing) and achieve low delay. In this embodiment, the CU 10b is connected to an Edge App (Edge Application Server) 70, which is an edge server having an application for providing low-delay services located at an edge site. Note that the edge site where the Edge App 70 is arranged may be the local accommodation station where the CU 10b is arranged.

For slice 3 (eMBB slice), both CU 10c and DU 20c are located in the regional accommodation station. This allows the DU 20c to be connected to a plurality of RUs 30 arranged at different antenna sites. In the configuration example of FIG. 2, the DU 20c is connected to a plurality of RUs 30 that form different cells, and inter-cell cooperation between the connected RUs (for example, CoMP (Coordinated Multi-Point Transmission/reception)). process. Thus, by enabling inter-cell cooperation, it is possible to improve radio communication quality.

FIG. 3 is a diagram showing a more specific configuration example of the base station system according to this embodiment. The DUs 20a, 20b and 20c respectively include schedulers 21a, 21b and 21c that perform scheduling for allocating radio resources to radio terminals. In the configuration example of FIG. 3, the schedulers 21a and 21b corresponding to slices 1 and 2 are arranged at antenna sites, and the scheduler 21c corresponding to slice 3 is accommodated in the local station. In this way, the schedulers 21a and 21b and the scheduler 21c have different placement locations.

DUs 20a, 20b, and 20c containing schedulers 21a, 21b, and 21c, respectively, are connected to a common RU 30, as described above. The schedulers 21a, 21b, and 21c use common radio resources available in the same cell formed by the common RU 30 to schedule radio terminals using corresponding slices. Radio resources used for scheduling by the schedulers 21a, 21b, and 21c are allocated in advance by the RAN controller 40. FIG.

<Device configuration>
The RAN controller 40 has a hardware configuration as shown in FIG. 4 as an example. Specifically, the RAN controller 40 has a CPU 101 , a ROM 102 , a RAM 103 , an external storage device 104 such as an HDD, and a communication device 105 .

In the RAN controller 40, the CPU 101 executes a program that implements each function of the RAN controller 40 and is stored in, for example, one of the ROM 102, the RAM 103, and the external storage device 104. FIG. Note that the CPU 101 may be replaced by one or more processors such as ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), DSPs (Digital Signal Processors), and the like.

The communication device 105 is a communication interface for communicating with external devices such as the CU 10 and DU 20 to be controlled under the control of the CPU 101 . The RAN controller 40 may have multiple communication devices 105 with different connection destinations.

Note that the RAN controller 40 may include dedicated hardware for executing each function described later, or a part may be executed by hardware and the other part may be executed by a computer that operates a program. Also, all functions may be performed by computers and programs.

CU10, DU20 and RU30 may also have a hardware configuration as shown in FIG. However, as the communication device 105, the RU 30 also has a wireless communication interface for wireless communication with wireless terminals in addition to the communication interface for communication with each DU 20. FIG.

FIG. 5 is a block diagram showing a functional configuration example of the RAN controller 40. As shown in FIG. The RAN controller 40 of this embodiment has a temporary allocation determination unit 51 , a first allocation processing unit 52 , a second allocation processing unit 53 and an allocation notification unit 54 . In the present embodiment, these functional units are realized on the CPU 101 by executing the control program by the CPU 101, but dedicated hardware for realizing each functional unit may be provided. Note that FIG. 5 shows only functional units related to allocation of radio resources to each scheduler 21 (allocation of radio resources used for scheduling for each slice to each of a plurality of slices) among the functions of the RAN controller 40. are shown, and functional units related to other functions are omitted.

The temporary allocation determination unit 51 performs temporary allocation of radio resources to each of a plurality of slices for isolation between slices with respect to radio resources used for scheduling in each slice. Specifically, the temporary allocation determination unit 51 determines a temporary allocation (temporary allocation amount) _Rtmp of radio resources for each of the plurality of slices according to a predetermined allocation ratio. The temporary allocation determination unit 51 outputs the determined temporary allocation R _tmp to the first allocation processing unit 52 .

The first allocation processing unit 52 performs a first allocation process of allocating radio resources to a plurality of slices with the temporary allocation R _tmp as the upper limit. The first allocation processing unit 52 outputs the radio resource allocation R _iso determined for the plurality of slices to the second allocation processing unit 53 .

The second allocation processing unit 53 allocates surplus radio resources that have not been allocated by the first allocation processing unit 52 among all radio resources available for allocation by the first allocation processing unit 52 to one or more slices. A second allocation process for allocating (re-allocating) is performed. The second allocation processing unit 53 outputs the radio resource allocation R determined for a plurality of slices as a final allocation.

The allocation notification unit 54 allocates radio resources that can be used for scheduling to the schedulers 21 (21a, 21b, 21c) corresponding to each slice based on the allocation R determined by the second allocation processing unit 53. send a notification indicating This completes allocation of radio resources to a plurality of slices.

<Timing of Allocating Radio Resources to Each Slice>
In this embodiment, the RAN controller 40 allocates (distributes) radio resources to each scheduler 21 (each slice) at predetermined time intervals. FIG. 6 is a diagram showing an example of timing of allocation of radio resources to each scheduler.

Here, in the architecture of the base station system like this embodiment, schedulers can be arranged at different locations (sites). In the configuration examples of FIGS. 2 and 3, the scheduler 21c is arranged at a location different from that of the schedulers 21a and 21b. When multiple schedulers corresponding to different slices are located at different locations, updating radio resource allocation for each scheduler (each slice) for each TTI (Transmission Time Interval), which is generally the minimum time unit for scheduling. is difficult.

Therefore, as shown in FIG. 6, the RAN controller 40 allocates radio resources (updates the allocation) to each scheduler every time interval ΔT longer than the TTI (eg, 100 TTIs). At that time, the RAN controller 40 allocates radio resources ( allocation). An example of the input parameters is the target value (target throughput) corresponding to the throughput defined by the SLA (service level agreement) of each slice, and the SINR (signal-to-interference and noise ratio) for each wireless terminal using each slice. ). Also, the average traffic demand at each slice is an example of an input parameter.

<First allocation process>
As described above, radio resource scheduling when network slicing is applied needs to achieve isolation between slices so that the slices do not affect each other. Specifically, the schedulers 21a, 21b, and 21c must use different radio resources to schedule radio terminals that use corresponding slices. The RAN controller 40 of the present embodiment allocates radio resources to each scheduler 21 (each slice) so as to ensure such isolation by the temporary allocation determining unit 51 and the first allocation processing unit 52 . Let L be the number of slices set for the plurality of CUs 10 and the plurality of DUs 20 by the RAN controller 40 below.

ｒ_tmp,sは、第１割当処理部５２による割り当てに使用可能な無線リソースの総量を基準とした、スライスｓ（ｓ＝１，２，...，Ｌ）に対する無線リソースの配分率を表す。各スライスに対する配分率は、例えば、複数のスライスのそれぞれに対する、ＳＬＡで定められた目標スループット（後述する予測スループットの目標値）Ｔ_tgt,sの比として予め定められる。この場合、スライスに対して定められた目標スループットが高いほど、より大きな配分率が当該スライスに対して定められ、目標スループットが低いほど、より小さな配分率が当該スライスに対して定められる。 The temporary allocation determination unit 51 determines a temporary allocation amount R _tmp of radio resources for each of a plurality of (L slices) according to a predetermined allocation ratio. R _tmp is represented as follows.

r _tmp,s represents the radio resource allocation ratio for slice s (s=1, 2, . . The allocation rate for each slice is predetermined, for example, as a ratio of the target throughput (target value of predicted throughput described later) T _tgt,s defined by the SLA for each of the plurality of slices. In this case, the higher the target throughput set for a slice, the larger the allocation rate for that slice, and the lower the target throughput, the smaller the allocation rate for that slice.

In this embodiment, the temporary allocation determination unit 51 temporarily allocates each slice so that the total amount of radio resources that can be used for allocation by the first allocation processing unit 52 is allocated to each slice according to a predetermined allocation ratio. Determine the quantity R _tmp .

ｒ_iso,sは、第１割当処理部５２による割り当てに使用可能な無線リソースの総量を基準とした、スライスｓ（ｓ＝１，２，...，Ｌ）に対する、第１割当処理における無線リソースの配分率を表す。 The first allocation processing unit 52 determines radio resource allocation R _iso by allocating radio resources to each of a plurality of (L slices) with the temporary allocation R _tmp as the upper limit. _Riso is expressed as follows.

r _iso,s is the radio resource in the first allocation process for slice s (s=1, 2, . Represents the resource allocation ratio.

Specifically, for each slice, the first allocation processing unit 52 obtains a predicted communication capacity (predicted throughput) while gradually increasing the radio resource amount r _iso,s to be allocated to the slice from 0. The predicted throughput is obtained for each slice based on the amount of radio resources allocated to that slice and the communication quality for that slice. The predicted throughput T _s of slice s (s=1, 2, . . . , L) is obtained as follows.

ここで、Ｎ_sは、スライスｓ内のユーザ数を表す。予測スループットＴ_sは、シャノンの定理に基づいて、次式により求められる。

ここで、ｎは、第１割当処理部５２による割り当てに使用可能な物理リソースブロック（ＰＲＢ）の総数、Ｂは、１ＰＲＢ（単位無線リソース）当たりの周波数帯域幅［Ｈｚ］、γⁱ _sは、スライスｓ内のユーザｉのＳＩＮＲを表す。なお、上式で用いたシャノンの定理は通信路限界を求めるものであるので、実際には、図７に示されるようなテーブルを用いて、単位周波数当たりのビットレートが求められる。 First, among the users using the slice s, the radio resource allocation r ⁱ _iso,s to the user i is expressed by the following equation using round robin.

where N _s represents the number of users in slice s. The predicted throughput T _s is obtained by the following equation based on Shannon's theorem.

Here, n is the total number of physical resource blocks (PRB) that can be used for allocation by the first allocation processing unit 52, B is the frequency bandwidth [Hz] per 1 PRB (unit radio resource), and _γ ^is Denote the SINR of user i in slice s. Since Shannon's theorem used in the above equation is used to determine the channel limit, in practice the bit rate per unit frequency is determined using a table such as that shown in FIG.

In this way, the first allocation processing unit 52 of the present embodiment uses _the ^SINRγis for each wireless terminal that uses the slice s as the communication quality for the slice s to obtain the predicted throughput _Ts .

The first allocation processing unit 52 increases the radio resource amount r _iso,s allocated to each slice s (s=1, 2, . . . , L) from 0, and the predicted throughput obtained as described above It is determined whether or not T _s satisfies a target value (target throughput T _tgt,s ) defined for the slice (T _s ≧T _tgt,s ).

When the predicted throughput T _s reaches the target throughput T _tgt,s while increasing the amount of radio resources to be allocated to the slice s, the first allocation processing unit 52 stops allocating radio resources to the slice. In addition, the first allocation processing unit 52 sets the amount of radio resources r _iso,s allocated to the slice s to the tentative allocation amount r _tmp , which is the upper limit, without the predicted throughput T _s reaching the target throughput T _tgt,s . Also when _s is reached, the allocation of radio resources to the slice is stopped.

FIG. 8A is a diagram showing an example of a radio resource allocation result by the first allocation processing unit 52. As shown in FIG. A case where the number of slices L=4 is shown as an example. In the example of FIG. 8A, for slices 1 and 3, the predicted throughput T _s reaches the target throughput T _tgt,s before r _iso,s of radio resources allocated to each slice reaches the upper limit ( ie the SLA is met). In this case, radio resources are not allocated up to the upper limit of the temporary allocation amount r _tmp,s , resulting in surplus radio resources (r _tmp,s −r _iso,s ). This surplus radio resource is used for the second allocation processing by the second allocation processing unit 53, and is allocated (reallocated) to other slices in order to increase the satisfaction of the SLAs for other slices. be.

On the other hand, in the example of FIG. 8A, for slices 2 and 4, the predicted throughput T _s does not reach the target throughput T _tgt,s , and r _iso,s of the radio resources allocated to each slice is the upper limit. The tentative allocation r _tmp,s has been reached (ie, r _iso,s =r _tmp,s ). In this case, surplus radio resources for slices 1 and 3 are further allocated by the second allocation processing by the second allocation processing unit 53 to slices 2 and 4 that have reached the allocation upper limit without satisfying the target throughput. be done.

In this way, the first allocation processing unit 52 determines, for each slice, the predicted communication capacity (predicted throughput T _s ) obtained based on the amount of radio resources to be assigned to the slice and the communication quality (SINR) for the slice. , until the target value (target throughput T _tgt,s ) determined for the slice is satisfied, radio resources are allocated to the slice with the temporary allocation amount r _tmp,s as the upper limit. Thereby, the first allocation processing unit 52 determines the radio resource allocation R _iso based on the temporary allocation R _tmp and outputs it to the second allocation processing unit 53 .

<Second Allocation Processing>
The second allocation processing unit 53 divides the surplus radio resources that have not been allocated by the first allocation processing unit 52 out of all radio resources available for allocation by the first allocation processing unit 52 into radio resources in order to satisfy the SLA. A second allocation process of allocating (re-allocating) to one or more slices lacking is performed.

In the present embodiment, the second allocation processing unit 53 selects the radios allocated by the first allocation processing unit 52 without satisfying the target value (target throughput T _tgt,s ) among the plurality of (L slices). For one or more slices (slices 2 and 4 in the example of FIG. 8) in which the amount of resources has reached the upper limit of the temporary allocation amount r _{tmp,s ,} the slices ( In the example, it allocates the surplus radio resources that were not allocated for slices 1 and 3).

なお、第１割当処理部５２による第１割当処理において、各スライスに割り当てる無線リソースｒ_iso,sが、仮割り当て量ｒ_tmp,sに達したスライス（図８の例では、スライス１及び３）については、ｒ_iso,s＝ｒ_tmp,sであるため、リソースプールＰに加えられる無線リソースの量は０となる。 Specifically, the second allocation processing unit 53 first adds radio resources that have not been allocated by the first allocation processing unit 52 to the resource pool P, as in the following equation.

In the first allocation processing by the first allocation processing unit 52, the slices (slices 1 and 3 in the example of FIG. 8) for which the radio resource r _iso,s allocated to each slice has reached the temporary allocation amount r _tmp,s , r _iso,s =r _tmp,s , so the amount of radio resources added to resource pool P is zero.

ｒ'_sは、第１割当処理部５２による割り当てに使用可能な無線リソースの総量を基準とした、スライスｓ（ｓ＝１，２，...，Ｌ）に対する、第２割当処理における無線リソースの配分率を表す。 Here, a radio resource allocation ratio R′ for each of a plurality of (L slices) for redistributing the radio resources included in the resource pool P is defined by the following equation.

r' _s is the radio resource in the second allocation process for the slice s (s = 1, 2, ..., L) based on the total amount of radio resources that can be used for allocation by the first allocation processing unit 52 represents the distribution ratio of

For one or more slices for which the target throughput T _tgt,s was not satisfied in the first allocation process, the second allocation processing unit 53 determines the degree of satisfaction of the predicted throughput with respect to the target throughput T _tgt,s (that is, the degree of satisfaction of the SLA ) is maximized, surplus radio resources (radio resources included in the resource pool P) are allocated to the one or more slices.

ただし、以下を条件とする。

Specifically, the second allocation processing unit 53 obtains R' that minimizes the evaluation function Φ(R') as in the following equation by solving the optimization problem.

However, the following conditions apply.

ここで、ｗ_sは、スライスｓ（ｓ＝１，２，...，Ｌ）に対して適用される重み、Φ_s(Ｒ')は、次式により定義される、各スライスに対応するコスト関数を表す。

このコスト関数は、対応するスライスｓについての目標スループットＴ_tgt,sに対する予測スループットＡ_s(Ｒ')の割合が所定値（例えば、１）に近いほど出力値が小さくなる。 The evaluation function Φ(R') described above is defined by the following equation using a cost function Φ _s (R') corresponding to slices s (s=1, 2, . . . , L).

where w _s is the weight applied to slice s (s=1, 2, . . . , L) and Φ _s (R′) corresponds to each slice, defined by represents the cost function.

This cost function has a smaller output value as the ratio of the predicted throughput A _s (R′) to the target throughput T _tgt,s for the corresponding slice s approaches a predetermined value (eg, 1).

The weight w _s applied to the cost function Φ _s (R') corresponding to each slice in the above evaluation function Φ(R') is, for example, according to the target throughput T _tgt,s determined by the SLA. Determined. The evaluation function Φ(R') is defined as the sum of cost functions Φ _s (R') weighted according to the weight w _s . By weighting the cost function Φ _s (R′) according to such weight w _s , it is possible to ensure fairness between slices in terms of SLA satisfaction in the allocation of radio resources in the second allocation process. be possible.

この予測スループットＡ_s(Ｒ')は、第１割当処理において求められる予測スループットＴ_sと同様、図７に示されるようなテーブルを用いて求められる。上式におけるｒ_sは、次式のように、スライスｓに対する最終的なリソース割り当てを表す。

The predicted throughput of slice s, which defines the cost function Φ _s (R') included in the above evaluation function Φ(R'), is obtained by the following equation.

This predicted throughput A _s (R') is obtained using a table such as that shown in FIG. 7, like the predicted throughput T _s obtained in the first allocation process. r _s in the above equation represents the final resource allocation for slice s as

Here, when the target throughput T _tgt,s defined by the SLA is satisfied for the slice s at the completion stage of the first allocation process (T _s ≧T _tgt,s ), that is, the SLA is satisfied If so, the amount r _s of radio resources finally allocated for slice s is the amount r _iso,s allocated in the first allocation process (r _s =r _iso,s ). On the other hand, when the target throughput T _tgt,s defined by the SLA is not satisfied for the slice s at the completion stage of the first allocation process (T _s <T _tgt,s ), that is, the SLA is not satisfied , r _s is the sum of the amount r _tmp,s allocated in the first allocation process and the amount r′ _s allocated in the second allocation process (r _s =r _tmp,s +r′ _s ) .

The _second allocation processing unit 53 performs a to reallocate the radio resources included in the resource pool P. That is, the second allocation processing unit 53 determines R' so as to minimize the output value of the evaluation function Φ(R'). This determines the final resource allocation r _s for each slice s (s=1, 2, . . . , L).

The second allocation processing unit 53 determines allocation R of radio resources to a plurality of (L number of) slices represented by the following equation as the final allocation, and outputs it to the allocation notification unit 54 .

FIG. 8B is a diagram showing an example of a radio resource allocation result by the second allocation processing unit 53. As shown in FIG. In the example of FIG. 8(B), the surplus radio resources for slices 1 and 3 shown in FIG. 8(A) are reallocated to slices 2 and 4 by the second allocation process described above. That is, the surplus radio resources for slices 1 and 3 whose SLA is satisfied by the first allocation process are reallocated to the remaining slices 2 and 4 so as to increase the satisfaction of the SLA for the remaining slices 2 and 4. It is

As described above, the RAN controller 40 of the present embodiment determines the amount of provisionally allocated radio resources for each of a plurality of slices according to a predetermined allocation ratio. For each slice, the RAN controller 40 allocates radio resources to the slice with the provisional allocation amount as the upper limit until the predicted communication capacity obtained for the slice satisfies the target value set for the slice. In addition, RAN controller 40 has not allocated to one or more slices for which the amount of allocated radio resources has been capped without the target being met, or to slices for which the target has been met. Allocate surplus radio resources.

According to the present embodiment, in the first allocation process, the RAN controller 40 allocates radio resources to each slice with the tentative allocation amount determined for each slice as the upper limit. As a result, when increasing the radio resources allocated to each slice, independent radio resource allocation is performed between slices within the range of the temporary allocation amount until the SLA is satisfied (until the target throughput T _s is satisfied). The RAN controller 40 stops allocating radio resources to slices that satisfy the SLA, and further allocates the surplus radio resources to slices that do not satisfy the SLA in the second allocation process. In this way, while ensuring isolation between slices, the second allocation process distributes radio resources to each slice so as to improve the quality of service provided by each slice (that is, increase the satisfaction of the SLA). It becomes possible to do

[Second embodiment]
In the second embodiment, as the second allocation processing by the second allocation processing unit 53, an example will be described in which surplus radio resources are allocated (reallocated) based on priorities set in advance for a plurality of slices. . Below, portions different from the first embodiment will be described.

In this embodiment, the second allocation processing by the second allocation processing unit 53 is different from that in the first embodiment. Among the one or more slices for which the target throughput (target value of predicted communication capacity) was not satisfied in the first allocation processing, the second allocation processing unit 53 selects each slice in descending order of preset priority. radio resources are allocated from surplus radio resources. At that time, the second allocation processing unit 53 obtains the predicted throughput A _s (R _′ ) of each slice (slice s), and uses surplus radio resources (resource pool P) to allocate radio resources.

More specifically, the second allocation processing unit 53 assigns allocations from the surplus radio resources to each target slice in descending order of priority among the target slices until there is no surplus radio resource. Allocate radio resources. For example, in the example of FIG. 8A, the second allocation process is performed on slices 2 and 4 as in the first embodiment. Here, if slice 2 has a higher preset priority than slice 4, surplus radio resources are allocated to slice 4 after surplus radio resource allocation to slice 2 is completed. Such allocation (reallocation) of radio resources is performed until there are no more surplus radio resources.

In this way, according to the second allocation process based on priority, in addition to the effect of the first embodiment, while increasing the possibility that a slice with a high priority satisfies the SLA, radio resources are allocated to each slice. becomes possible to do.

Various settings are possible for the priority set in advance for each slice described above, as described below.

●Priority setting based on SINR (communication quality) The second allocation processing unit 53 can set the priority for a plurality of slices so that the higher the communication quality for each of the plurality of slices, the higher the priority. . In this case, for example, the average SINR (that is, the average value of SINR for all PRBs of all users in the target slice) in the immediately preceding predetermined period (time interval ΔT) is used as the communication quality for priority setting. By performing the second allocation process based on such priority setting, it is possible to further improve the frequency utilization efficiency.

●Priority setting based on permissible delay The second allocation processing unit 53 can set the priority for each of a plurality of slices so that the smaller the permissible delay for each of the slices, the higher the priority. By performing the second allocation process based on such priority setting, for example, it is possible to shorten the queue required for a slice with a small allowable delay, such as a slice corresponding to URLLC. .

●Priority setting by PF (Proportional Fairness) method The second allocation processing unit 53 can set priorities for a plurality of slices using the PF method. In this case, the second allocation processing unit 53 calculates the average value of predicted throughput (predicted communication capacity) per unit radio resource (1 PRB) in a plurality of past predetermined periods (ΔT) for each of a plurality of slices. The priority of a plurality of slices is set such that the higher the ratio of the predicted throughput per unit radio resource in the predetermined period (ΔT) of , the higher the priority.

By performing the second allocation process based on such priority setting, it becomes possible to allocate surplus radio resources in the second allocation process in consideration of communication quality and fairness between slices. . As a result, it is possible to give an opportunity to allocate surplus radio resources even to slices in which radio terminals with low SINR exist.

-Priority setting based on SLA achievement rate A plurality of slices may be prioritized such that the smaller the degree of achievement, the higher the priority. By performing the second allocation process based on such priority setting, it is possible to improve fairness between slices in allocation of surplus radio resources from the viewpoint of the degree of achievement of SLA.

[Third embodiment]
In the third embodiment, as the second allocation processing by the second allocation processing unit 53, an example will be described in which surplus radio resources are allocated (reallocated) to a plurality of slices according to weights respectively determined. Below, portions different from the first and second embodiments will be described.

In this embodiment, the second allocation processing by the second allocation processing unit 53 is different from the first and second embodiments. The second allocation processing unit 53 presets weights for a plurality of slices as parameters, and allocates radio resources from surplus radio resources (resource pool) in the second allocation process according to the ratio of the weights of the slices. I do. Specifically, the second allocation processing unit 53, according to the weight determined for one or more slices for which the target throughput (target value of predicted communication capacity) was not satisfied in the first allocation process, Surplus radio resources are allocated to the one or more slices.

Thus, according to the second weight-based allocation process, it is possible to evenly distribute surplus radio resources according to weights to one or more slices for which the target throughput was not satisfied in the first allocation process. be possible. As a result, unlike the second embodiment, when there are no radio resources in the resource pool P due to allocation to slices with high priority, surplus radio resources are not allocated to slices with low priority. can be avoided.

Various settings are possible for the weight preset for each slice described above, as described below.

●Weight setting by PF method The second allocation processing unit 53 can set weights for a plurality of slices by using the PF method. In this case, the second allocation processing unit 53 calculates the average value of the predicted throughput (predicted communication capacity) per unit radio resource (1 PRB) in a plurality of past predetermined periods (ΔT) for each of the plurality of slices, A ratio of predicted throughput per unit radio resource in a predetermined period (ΔT) is set as a weight for the slice.

By performing the second allocation process based on such weight settings, it is possible to allocate (distribute) surplus radio resources in the second allocation process in consideration of communication quality and fairness between slices. become. As a result, it is possible to give an opportunity to allocate surplus radio resources even to slices in which radio terminals with low SINR exist.

Weight setting based on the SLA achievement rate The second allocation processing unit 53 calculates the predicted throughput at the end of allocation by the first allocation processing unit 52 for each of a plurality of slices with respect to the target throughput (target value of predicted communication capacity). The inverse of the ratio (ie, SLA achievement) is set as the weight for that slice.
By performing the second allocation process based on such weight settings, it is possible to improve fairness in allocation of surplus radio resources among slices in terms of the degree of achievement of SLA.

[Fourth Embodiment]
In the fourth embodiment, as the second allocation processing by the second allocation processing unit 53, the temporary allocation of the wireless resources performed in the first allocation processing and the allocation to the wireless resources based on the temporary allocation are performed until there is no surplus wireless resource. An example of repeated operations will be described. Below, portions different from the first to third embodiments will be described.

In the present embodiment, the second allocation processing unit 53 performs provisional allocation R _tmp determined by the temporary allocation determination unit 51 for one or more slices for which the target throughput was not satisfied in the first allocation processing. , the allocation of the radio resources contained in the resource pool P is repeated.

Specifically, the second allocation processing unit 53 first temporarily allocates surplus radio resources (resource pool P) according to a predetermined allocation ratio (R _tmp ) to each of the one or more slices. I do. Further, the second allocation processing unit 53 allocates radio resources to each slice up to the amount of the temporarily allocated radio resources until the predicted throughput satisfies the target throughput. The second allocation processing unit 53, similar to the first allocation process, completes the allocation with the temporary allocation amount as the upper limit, and configures the resource pool P again with surplus resources at that time. The second allocation processing unit 53 repeats the above-described temporary allocation and allocation of radio resources included in the resource pool P until there are no surplus radio resources.

According to the present embodiment, the allocation of radio resources included in the resource pool P is repeated based on the temporary allocation R _tmp until there is no surplus radio resource, thereby increasing the fairness of radio resource allocation between slices. becomes possible.

[Other embodiments]
The wireless communication device according to the above-described embodiments can be realized by a computer program for causing a computer to function as a wireless communication device. The computer program can be stored in a computer-readable storage medium and distributed, or can be distributed via a network.

10: CU, 20: DU, 21: Scheduler, 30: RU, 40: RAN Controller, 50: 5GC UPF, 60: 5GC CPF, 70: Edge Application, 101: CPU, 102: ROM, 103: RAM, 104: external storage device, 105: communication device

Claims (23)

A control device that allocates radio resources used for scheduling for each slice to each of a plurality of slices,
determining means for determining a temporary allocation amount of radio resources for each of the plurality of slices according to a predetermined allocation ratio;
For each slice, the temporary allocation amount is set as the upper limit until the predicted communication capacity obtained based on the amount of radio resources allocated to the slice and the communication quality of the slice satisfies the target value set for the slice. a first allocation means for allocating radio resources to the slice as
Among the plurality of slices, the target value is satisfied for one or more slices in which the amount of radio resources allocated by the first allocation means reaches the upper limit without the target value being satisfied. a second allocation means for allocating surplus radio resources that have not been allocated to slices;
A control device comprising: The first allocation means increases the amount of radio resources allocated to the slice for each slice, while the amount of radio resources allocated to the slice reaches the temporary allocation amount that is the upper limit, or When the predicted communication capacity reaches the target value, stop allocation of radio resources for the slice,
The surplus radio resources are the amount of radio resources obtained by subtracting the total amount of radio resources allocated to the plurality of slices by the first allocation means from the total amount of the provisional allocation amount to the plurality of slices. The control device according to claim 1, characterized by: The second allocation means allocates the surplus radio resource to the one or more slices so as to maximize satisfaction of the predicted communication capacity with respect to the target value for the one or more slices. 3. The control device according to claim 1 or 2, characterized in that: Using a cost function corresponding to each of the one or more slices, wherein the ratio of the predicted communication capacity to the target value for the corresponding slice is closer to a predetermined value, the smaller the output value is, using the cost function, is defined and
4. The second allocation unit allocates the surplus radio resource to the one or more slices so as to minimize an output value of the evaluation function. 2. The control device according to item 1. Weighting according to the target value is performed on the cost function corresponding to each of the one or more slices,
5. The control device according to claim 4, wherein the evaluation function is defined as a sum of the weighted cost functions respectively corresponding to the one or more slices. The second allocation means, among the one or more slices, assigns the surplus wireless network to each slice in descending order of preset priority so that the predicted communication capacity satisfies the target value. 3. The control device according to claim 1 or 2, allocating radio resources from resources. The second allocation unit allocates radio resources from the surplus radio resources to each slice in order from the slice with the highest priority until the surplus radio resources are exhausted. 7. The control device according to 6. 8. The apparatus according to claim 6 or 7, further comprising setting means for setting the priority for the plurality of slices such that the higher the communication quality for each of the plurality of slices, the higher the priority. Control device as described. 8. The apparatus according to claim 6, further comprising: setting means for setting the priority for the plurality of slices such that the smaller the allowable delay for each of the plurality of slices, the higher the priority. controller. For each of the plurality of slices, the larger the ratio of the predicted communication capacity per unit radio resource in the preceding predetermined period to the average value of the predicted communication capacity per unit radio resource in a plurality of past predetermined periods, the higher the 8. The control device according to claim 6, further comprising setting means for setting the priority for the plurality of slices so that the priority is high. For each of the plurality of slices, the priority for the plurality of slices is such that the smaller the ratio of the predicted communication capacity at the end of allocation by the first allocation unit to the target value, the higher the priority. 8. The control device according to claim 6 or 7, further comprising setting means for setting . 2. The second allocation unit allocates the surplus radio resource to the one or more slices according to weights respectively determined for the one or more slices. Or the control device according to 2. For each of the plurality of slices, the ratio of the predicted communication capacity per unit radio resource in the preceding predetermined period to the average value of the predicted communication capacity per unit radio resource in a plurality of past predetermined periods is calculated for the slice 13. The control device according to claim 12, further comprising setting means for setting the weight. further comprising setting means for setting, for each of the plurality of slices, the reciprocal of the ratio of the predicted communication capacity at the end of allocation by the first allocation means to the target value as the weight for the slice. 13. The control device according to claim 12. The second allocation means temporarily allocates the surplus radio resources to each of the one or more slices according to the predetermined allocation ratio, and the predicted communication capacity satisfies the target value. 3. The process of allocating radio resources to the slice with the amount of the temporarily allocated radio resources as an upper limit is repeated until there is no surplus radio resource. Control device. The determination means determines a temporary allocation amount for each slice so that the total amount of radio resources available for allocation by the first allocation means is allocated to each slice according to the predetermined allocation ratio. 16. The control device according to any one of claims 1 to 15. 17. The control device according to any one of claims 1 to 16, wherein said predetermined distribution ratio is determined as a ratio of said target value to each of said plurality of slices. 2. From claim 1, wherein the first assigning means obtains the predicted communication capacity using SINR (signal-to-interference plus noise ratio) for each wireless terminal using the corresponding slice as the communication quality. 18. The control device according to any one of 17. The control device according to any one of claims 1 to 18, wherein the target value is a target value corresponding to throughput defined by SLA (Service Level Agreement) for each slice. The first and second allocation means allocate radio resources to a plurality of schedulers respectively corresponding to the plurality of slices,
Each of the plurality of schedulers uses the corresponding slice using the radio resources allocated by the first and second allocation means every predetermined period within the same cell formed by one radio unit. 20. The control device according to any one of claims 1 to 19, wherein scheduling is performed for allocating radio resources to radio terminals that The plurality of schedulers are arranged in one or more DUs (Distributed Units),
The wireless unit and the one or more DUs constitute a base station system,
the wireless unit is located at an antenna site of the base station system;
The control device according to claim 20, wherein the control device is communicably connected to the base station system. A control method executed by a control device that allocates radio resources used for scheduling for each slice to each of a plurality of slices,
a determination step of determining a temporary allocation amount of radio resources for each of the plurality of slices according to a predetermined allocation ratio;
For each slice, the temporary allocation amount is set as the upper limit until the predicted communication capacity obtained based on the amount of radio resources allocated to the slice and the communication quality of the slice satisfies the target value set for the slice. A first allocation step of allocating radio resources to the slice as
Among the plurality of slices, the target value is satisfied for one or more slices in which the amount of radio resources allocated in the first allocation step reaches the upper limit without the target value being satisfied. a second allocation step of allocating surplus radio resources that have not been allocated to the slice;
A control method comprising: A program for causing a computer included in a control device to execute the control method according to claim 22.

Images