JP7627669B2 - Wireless communication system, and method and program for rearranging units therein - Google Patents

Description

The present invention relates to a wireless communication system and a method and program for rearranging units thereof, and in particular to a wireless communication system and a method and program for rearranging units thereof that improves communication quality such as throughput and delay time by controlling the position of a base station device (unit) and the direction of radio waves.

As fifth-generation wireless communication systems (5G) become more advanced, it is expected that the demand for high-capacity, low-latency, and multi-connection communications will further increase compared to the early days of their introduction. In addition, as 5G is widely used in a wide variety of services such as robot control, connected cars, and AR/VR, it is becoming increasingly important to simultaneously satisfy the required quality for each individual service.

In order to meet the quality requirements of diversified services, Non-Patent Document 1 proposes RAN slicing technology, which divides a radio access network (RAN) consisting of multiple base stations into multiple logical networks (slices) and flexibly customizes the slices according to the service.

On the other hand, Non-Patent Document 2 discloses Massive MIMO technology, which simultaneously allocates resources to multiple terminals located in the same direction by directing a narrow beam from a base station antenna in a specific direction.

The O-RAN Alliance is also working on specifications to split the functions of base stations, which were previously integrated, into a Centralized Unit (CU) that performs session processing, a Distributed Unit (DU) that performs baseband processing, and a Radio Unit (RU) that performs radio processing, and to open up the interface specifications between each unit. The O-RAN Alliance is also working on specifications for a RAN controller (RAN Intelligent Controller: RIC) that will provide integrated control of the RAN.

Furthermore, as each function of a base station becomes smaller and robot and drone technology advances, it is expected that the mobility of each function will increase. Patent Document 1 considers technology that uses a movable Wi-Fi AP to avoid communication congestion with the aim of offloading traffic in a wireless communication system.

JP 2018-11156 A

Shunliang Zhang, "An Overview of Network Slicing for 5G," IEEE Wireless Communications, pp. 111-117, April 2019. Erik G. Larsson et al., "Massive MIMO for next generation wireless systems," IEEE Communications Magazine, pp. 186-195, Feb. 2014.

In the past, in order to improve the communication quality of wireless communication systems, technologies have been considered such as dividing the network for each service or using Massive MIMO technology to generate narrow beams and divide space. However, since these do not control the physical location of the base station, it is difficult to deal with localized traffic congestion.

Meanwhile, technology is being considered that uses movable Wi-Fi APs to offload traffic in congested areas. However, because Wi-Fi APs are separate systems from the wireless communication system, there is a problem in that integrated control is not possible.

The object of the present invention is to provide a wireless communication system and a method and program for rearranging units thereof that can solve the above technical problems and improve communication quality such as throughput and delay time by controlling the position of base station devices (units) and the direction of radio waves.

To achieve the above object, the present invention is characterized in that a wireless communication system in which multiple wireless base stations are controlled by a RAN controller, each of which includes at least one of a session unit (CU), a distributed unit (DU) and a radio unit (RU), and in which the interfaces between the units are open, is provided with the following configuration.

(1) The system includes a means for notifying the RAN controller of the location of each RU, a means for detecting a radio base station where traffic is increasing and notifying the RAN controller, a means for calculating in the RAN controller the relocation of each RU so that the increasing traffic is distributed to other radio base stations, and a means for relocating each RU based on the result of the calculation of the relocation.

(2) The system further includes a means for notifying the RAN controller of the direction of radio waves for each RU to communicate with a wireless terminal, and the means for calculating the rearrangement further calculates the rearrangement of the direction of radio waves for each RU.

(3) The system further includes a means for notifying the RAN controller of location information of the DUs connected to each RU, and the means for calculating the rearrangement further calculates the rearrangement of each DU.

(1) It is now possible to relocate RUs of other wireless base stations near RUs of a wireless base station where traffic is increasing, making it possible to distribute and process local increases in traffic volume among multiple RUs. This makes it possible to improve communication quality, such as throughput and delay time, even in cases where wireless terminals are locally concentrated and traffic density temporarily becomes very high.

(2) In addition to the location of the RU, the direction of the radio waves can also be optimized by rearrangement, so that more radio waves can be directed in the direction of more wireless terminals, further improving communication quality such as throughput and latency.

(3) The location of the DU connected to the relocated RU can also be relocated, expanding the range in which the RU can be relocated.

FIG. 1 is a functional block diagram showing the configuration of a main part of a radio access network (RAN) to which the present invention is applied. 13 is a sequence flow showing a procedure in which the distributed unit DU and the radio unit RU notify the RAN controller of information regarding their own positions and radio wave directions. 13 is a sequence flow showing a procedure for detecting a local increase in traffic and dynamically relocating the positions of the distributed units DU and radio units RU and the direction of radio waves by the antennas ANT of the radio units RU. 11 is a flowchart showing a procedure in which the RAN controller calculates the positions of the distributed unit DU and the radio unit RU, and relocation of the radio wave direction of the radio unit RU. FIG. 13 is a diagram showing an example of calculation for rearrangement of the position of a wireless unit RU and the direction of radio waves.

The following describes in detail an embodiment of the present invention with reference to the drawings. Figure 1 is a functional block diagram showing the configuration of the main parts of a radio access network (RAN) to which the present invention is applied, and configuration that is not necessary for the explanation of the present invention is omitted here. In the present invention, the interfaces between the session unit CU, distributed unit DU, and radio unit RU of each radio base station are standardized and opened according to specifications that comply with the O-RAN Alliance.

The radio access network RAN accommodates multiple radio base stations, each of which includes at least one of a session unit CU, a distributed unit DU, and a radio unit RU. Base station A includes all of the CU, DU, and RU, base stations B1 and C1 include CU and DU, base station D1 includes a CU, base station D2 includes a DU, and base stations B2, C1, C2, and D3 include RUs.

Each CU of base stations A, B1, C1, and D1 is connected to the core network CN via the backhaul. The CU of each base station is connected to the DU of the same base station or other corresponding base stations via the midhaul. The DU of each base station is connected to the RU of the same base station or other corresponding base stations via the fronthaul.

The CU and DU of each base station are connected to the RAN controller via a control signal interface, and can control slices, bandwidth, Massive MIMO, etc. The RAN controller and DU exchange information about the current location and the direction of radio waves for communicating with wireless terminals via the control signal interface, and the RU connected to each DU exchange information with each other via the fronthaul.

The radio access network RAN periodically acquires information about the location of each DU and each RU, as well as the direction of radio waves for communicating with wireless terminals, and detects local increases in traffic. It then relocates the locations of the DUs and RUs and the direction of the RU radio waves based on the information about the locations and radio wave directions so that the locally increased traffic is distributed to other wireless base stations.

Each RU is mounted on a mobile unit _VRU such as a vehicle, robot, or drone, and can move to a designated relocation position. The DU is mounted on a mobile unit _VDU , and can move to a designated relocation position. Each mobile unit _VRU , _VDU moves the mounted DU and RU to their relocation positions based on the results of the relocation calculation. Each RU repositions the direction of radio waves for communicating with a wireless terminal via an antenna ANT based on the results of the relocation calculation.

In addition to the functions of a typical RU, each RU is equipped with a location acquisition unit 101 that locates its current location using an appropriate system such as GPS, and a direction control unit 102 that controls the direction of radio waves. In addition to the functions of a typical DU, each DU is equipped with a location acquisition unit 201 that locates its current location using an appropriate system such as GPS, and a traffic increase detection unit 202 that detects excessive increases in the number of connected terminals and traffic.

In addition to the functions of a general RAN controller, the RAN controller also includes a rearrangement calculation unit 301 and a rearrangement unit 302. The rearrangement calculation unit 301 calculates rearrangement of the positions of the DUs and RUs and the direction of radio waves based on information about the positions of the DUs and RUs and the direction of radio waves of each RU, so that increased traffic at some base stations is distributed to other base stations. The rearrangement unit 302 instructs each mobile unit V DU , V _RU equipped with a _DU , RU to move the DU, RU based on the calculation result of the rearrangement, and further instructs the direction control unit 102 of the RU to change the direction of radio waves.

Figure 2 shows a sequence flow that shows the procedure by which the distributed unit DU and the radio unit RU notify the RAN controller of information regarding their own positions and the direction of radio waves, and is executed repeatedly at a specified interval.

The RU acquires its current position _PRU using a position acquisition unit 101, acquires the current direction _DANT pointed by each antenna ANT using a direction control unit 102, and transmits this to the DU at time t1. If the RU supports Massive MIMO, it acquires the beam direction as the radio wave direction _DANT .

The DU acquires its own current position _PDU in the position acquisition unit 201 and transmits it to the RAN controller at time t2 together with the position P _Ru and the radio wave direction D _ANT acquired from the RU. The RAN controller updates and registers the received information on the position P _RU , _PDU , and radio wave direction D _ANT .

Figure 3 shows a sequence flow diagram of the procedure for detecting a local increase in the number of connected terminals or wireless traffic and dynamically relocating the positions of the distributed unit DU and wireless unit RU as well as the direction of the wireless unit RU's radio waves using the antenna ANT.

When the traffic increase detection section 202 of a certain distributed unit DU (DU _T ) detects an increase in the number of radio terminals MN connected to the radio unit RU or an increase in the amount of radio traffic, at time t11, the distributed unit DU _T transmits traffic increase information to the RAN controller via the control signal interface.

This traffic increase information describes an ID and traffic volume unique to the distributed unit DU _T. In response to receiving the traffic increase information, the RAN controller calculates the position of each distributed unit DU and radio unit RU, and relocation of each RU with respect to the direction of radio waves.

FIG. 4 is a flowchart showing a procedure for the RAN controller to calculate rearrangement. In step S1, the location of the wireless unit RU _T to which the distributed unit DU _T that has transmitted the traffic increase information is connected is obtained based on the location information of the RU that is periodically updated and registered.

In step S2, the top N wireless units RU that are closest to the wireless unit _RUT are selected as candidates for rearrangement. In step S3, the rearrangement targets are narrowed down from the N wireless units RU to the top n (n≦N) wireless units RU with the most free resource capacity. In step S4, a rearrangement calculation is performed to distribute the narrowed down n wireless units RU in the vicinity of the wireless unit _RUT .

In this embodiment, positions to rearrange the n RUs are calculated so that a large number of wireless terminals MN connected to the wireless unit RU _T can be handed off to the n RUs after rearrangement in a proportion that corresponds to the available capacity. In step S5, directions for rearranging the n wireless units RU after rearrangement are calculated so that radio waves from the n wireless units RU after rearrangement are directed toward more directions where there are more wireless terminals MN.

Figure 5 shows an example of calculating the relocation of a radio unit RU and its antenna ANT. Each of base stations 50-57 includes a radio unit RU, and shows a case in which an increase in traffic is detected in base station 50.

First, the top five RUs (base stations 51-56) that are closest to base station 50 are selected as candidates for relocation, and then the relocation targets are narrowed down from the five base stations 51-56 to the top four base stations 51-55 with the most free resource capacity. Then, the relocation positions of the narrowed down four base stations 51-55 are calculated, and further the direction in which to relocate the radio waves of each wireless unit RU is calculated.

Returning to FIG. 4, in step S6, the necessity of rearrangement is determined for each distributed unit DU to which the n wireless units RU are connected after rearrangement. In this embodiment, a distributed unit DU whose distance from the wireless unit RU after rearrangement exceeds a predetermined threshold is determined to require rearrangement, and the process proceeds to step S7, where the position to rearrange the distributed unit DU is calculated.

In this embodiment, a suitable location where the distance from the connected wireless unit RU and session processing unit CU is both less than or equal to a predetermined threshold is calculated as the position for relocating the distributed unit DU.

Returning to FIG. 3, at time t12, the calculation result of the rearrangement is transmitted to the corresponding distributed unit DU via the control signal interface. If the targets of rearrangement are the distributed unit DU, the radio unit RU and its antenna ANT, the position to which the distributed unit DU is to be rearranged, the position to which the radio unit RU is to be rearranged and the direction in which the radio waves are to be rearranged are transmitted.

When the distributed unit DU receives the rearrangement calculation result, it extracts the position to rearrange the connected radio unit RU and the rearrangement direction of the radio wave, and transmits it to the radio unit RU via the fronthaul at time t13. Also, if the rearrangement calculation result includes the position to rearrange the distributed unit DU, it instructs its own mobile station _VDU to move to the rearrangement position.

When the wireless unit RU receives the rearrangement calculation result from the distributed unit DU, it instructs its own mobile unit _VRU to move to the rearrangement position, and causes the direction control unit 102 to rearrange the radio wave direction.

According to this embodiment, it becomes possible to relocate RUs of other wireless base stations near RUs of a wireless base station where traffic is increasing, making it possible to distribute the processing of local increases in traffic volume among multiple RUs, thereby improving communication quality such as throughput and delay time.

In addition, according to this embodiment, in addition to the RU, the orientation and beam direction of its antenna ANT are also optimized by rearrangement, so that more radio waves can be directed in the direction where there are more wireless terminals, thereby further improving communication quality such as throughput and delay time.

Furthermore, according to this embodiment, the position of the DU connected to the relocated RU can also be relocated, so the range in which RUs can be relocated can be expanded.

The above-described embodiment makes it possible to improve communication quality, such as wireless communication throughput and latency, and thus provide a variety of communication and entertainment to many people regardless of geographic or economic disparity. As a result, it will be possible to contribute to the achievement of Goal 9 "Build resilient infrastructure and promote inclusive and sustainable industrialization" and Goal 11 "Make cities inclusive, safe, resilient and sustainable" of the United Nations-led Sustainable Development Goals (SDGs).

101... position acquisition unit, 102... direction control unit, 201... position acquisition unit, 202... traffic increase detection unit, 301... rearrangement calculation unit, 302... rearrangement unit

Claims (13)

In a wireless communication system in which a plurality of wireless base stations are controlled by a RAN controller, each of the wireless base stations includes at least one of a session unit (CU), a distributed unit (DU) and a radio unit (RU), and the interfaces between the units are open,
means for reporting the location of each RU to a RAN controller;
A means for detecting a radio base station where traffic is increasing based on a radio traffic volume and notifying a RAN controller of the detection;
a means for calculating a relocation of each RU in a RAN controller so that the increasing traffic is distributed to other radio base stations;
and means for rearranging each RU based on a result of the rearrangement calculation. The wireless communication system according to claim 1, characterized in that the means for calculating the rearrangement performs the rearrangement calculation so that other RUs are distributed and arranged near the RU connected to the wireless base station where traffic is increasing. The wireless communication system according to claim 1 or 2, characterized in that the relocation means moves the first mobile body carrying the RU to a position according to the calculation result of the relocation. The method further includes: notifying a RAN controller of a direction of radio waves for each RU to communicate with a radio terminal;
4. The wireless communication system according to claim 1, wherein the means for calculating rearrangement further calculates rearrangement of a radio wave direction of each RU to be rearranged. The method further includes: notifying a RAN controller of location information of each DU;
5. The wireless communication system according to claim 1, wherein the means for calculating rearrangement further calculates rearrangement of a DU connected to a RU to be rearranged. The wireless communication system according to claim 5, characterized in that the means for calculating the rearrangement calculates the rearrangement of each DU based on the position of the CU to which each DU is connected and the position of the RU after rearrangement. The wireless communication system according to claim 5 or 6, characterized in that the relocation means moves the second mobile body carrying the DU to a position according to the calculation result of the relocation. A unit rearrangement method for a wireless communication system in which a plurality of wireless base stations are controlled by a RAN controller, each of the wireless base stations includes at least one of a session unit (CU), a distributed unit (DU) and a radio unit (RU), and an interface between the units is open, comprising:
Notify the RAN controller of the location of each RU;
Detects wireless base stations with increasing traffic based on wireless traffic volume and notifies the RAN controller,
Calculating a relocation of each RU in a RAN controller so that the increasing traffic is distributed to other radio base stations;
A unit rearrangement method for a wireless communication system, comprising: rearranging each RU based on a result of the rearrangement calculation. Each RU notifies the RAN controller of the direction of radio waves for communication with wireless terminals,
When calculating the relocation, further calculate the relocation of the radio wave direction of each RU to be relocated;
9. The method for rearranging units in a wireless communication system according to claim 8, further comprising rearranging the direction of radio waves. The location information of each DU is notified to the RAN controller.
When calculating the relocation, further calculate the relocation of a DU connected to the RU to be relocated;
The unit rearrangement method for a wireless communication system according to claim 8 or 9, characterized in that the position of each DU is rearranged. A unit relocation program for a wireless communication system in which a plurality of wireless base stations are controlled by a RAN controller, each of the wireless base stations includes at least one of a session unit (CU), a distributed unit (DU) and a radio unit (RU), and an interface between the units is open, comprising:
A procedure for notifying the RAN controller of the location of each RU;
A procedure for detecting a wireless base station where traffic is increasing based on wireless traffic volume and notifying the RAN controller;
A procedure of calculating a relocation of each RU in a RAN controller so that the increasing traffic is distributed to other radio base stations;
and a procedure for rearranging each RU based on a result of the rearrangement calculation. The method further includes a procedure for each RU notifying a RAN controller of a direction of radio waves for communicating with a wireless terminal;
The step of calculating the rearrangement further includes calculating the rearrangement of the radio wave direction of each RU to be rearranged;
12. The unit rearrangement program for a wireless communication system according to claim 11, further comprising the step of rearranging the directions of radio waves. The method further includes a procedure for notifying a RAN controller of location information of each DU,
The step of calculating the rearrangement further includes calculating a rearrangement of a DU connected to the RU to be rearranged;
13. The unit rearrangement program for a wireless communication system according to claim 11, further comprising: a step of rearranging the positions of the DUs.

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