WO2019180849A1

WO2019180849A1 - Base station

Info

Publication number: WO2019180849A1
Application number: PCT/JP2018/011197
Authority: WO
Inventors: 輝朗戸枝; アニールウメシュ; 明人花木; 寛王
Original assignee: 株式会社Ｎｔｔドコモ
Priority date: 2018-03-20
Filing date: 2018-03-20
Publication date: 2019-09-26

Abstract

Disclosed is a technology that enables a plurality base stations to wirelessly communicate with a user device, in a state where the base stations are linked. One embodiment relates to a base station including: a control unit that determines the state of the base station; and a transmission unit that transmits, multiple times, information indicating the determined state to another base station.

Description

base station

The present invention relates to a wireless communication system.

Currently, the fifth generation (5G) communication standard is being studied as the next generation communication standard of LTE (Long Term Evolution) and LTE-Advanced. In the new radio access technology (NR) in the fifth generation, as a communication scheme for a plurality of RAN (Radio Access Network) nodes or base stations to perform radio communication with a user equipment (User Equipment: UE), CU- DU (Central Unit-Distributed Unit) split, LTE-NR dual connectivity, etc. are being studied.

An object of the present invention is to provide a technique for wireless communication with a user apparatus in cooperation with a plurality of base stations.

In order to solve the above-described problem, an aspect of the present invention is a base station, which includes a control unit that determines a state of the base station, and a transmission that transmits information indicating the determined state to other base stations a plurality of times And a base station.

According to the present invention, it is possible to provide a technique for wireless communication between a plurality of base stations in cooperation with a user apparatus.

It is a block diagram which shows a CU-DU split. It is a block diagram which shows LTE-NR dual connectivity. It is a figure which shows the protocol stack of the lower layer used for U-plane of NR system. 1 is a schematic diagram illustrating a wireless communication system according to an embodiment of the present invention. It is a block diagram which shows the function structure of the base station by one Example of this invention. FIG. 4 is a diagram illustrating information elements of a DDDS according to an embodiment of the present invention. FIG. 4 is a diagram illustrating information elements of a DDDS according to an embodiment of the present invention. It is a figure which shows the transmission opportunity of DDDS by one Example of this invention. It is a figure which shows the transmission opportunity of DDDS by one Example of this invention. It is a block diagram which shows the hardware constitutions of the user apparatus by one Example of this invention, and a base station.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the following embodiments, a wireless communication system in which a plurality of base stations or nodes cooperate to realize wireless communication with a user apparatus is disclosed.

In communication schemes such as CU-DU split, LTE-NR dual connectivity, etc., in which a plurality of base stations or nodes cooperate to realize wireless communication with a user apparatus, data is transmitted as U- It is transferred between base stations or nodes using a plane.

For example, in the CU-DU split shown in FIG. 1, the base station (gNB) performs functional splitting between the upper layer split and the lower layer split. In CU-DU split, upper layer split is provided by CU (Central Unit), lower layer split is provided by DU (Distributed Unit), and data is exchanged between CU and DU using U-plane. Is done. Here, the upper layer is realized by a CU having a PDCP (Packet Data Convergence Protocol) entity, and the lower layer is realized by a DU having no PDCP entity.

In the LTE-NR dual connectivity shown in FIG. 2, the LTE base station (eNB) and the NR base station (gNB) cooperate with each other to simultaneously communicate with the user apparatus, and between the eNB and the gNB, U- Data is exchanged using the plane.

Note that a communication scheme in which a plurality of base stations or nodes cooperate to realize wireless communication with a user apparatus is not limited to the illustrated embodiment, and, for example, dual connectivity (multiple connectivity within the same RAT (Radio Access Technology)) 1), a combination of the embodiments shown in FIG. 1 and FIG. 2, and transmission / reception of data between three or more nodes and the user apparatus.

In U-plane, a protocol stack as shown in FIG. 3 is used in the lower layer. The lower layer does not include a PDCP entity, and the lower layer protocol does not have functions such as packet loss detection and a retransmission mechanism. For this reason, reliability is not ensured compared with the upper layer. Therefore, information that requires reliability needs to be secured by an upper layer protocol, but in the current NR, such a mechanism is introduced only in one direction from the upper node to the lower node. For this reason, in the following embodiments, a technique for reliably transmitting information that requires reliability (for example, control information, status notification, etc.) from the lower node to the upper node is provided.

In an embodiment described later, a base station that functions as a lower node transmits information indicating the state of the own station to other base stations that function as an upper node a plurality of times. This makes it possible to reliably transmit information that requires reliability from the lower node to the upper node.

First, a radio communication system according to an embodiment of the present invention will be described with reference to FIG. FIG. 4 is a schematic diagram illustrating a wireless communication system according to an embodiment of the present invention.

As shown in FIG. 4, the wireless communication system 10 includes a user device 50 and

base stations

100 and 200.

The

base stations

100 and 200 cooperate with each other for wireless communication with the user apparatus 50. In this embodiment, the base station 100 functions as a lower node that does not include a PDCP entity, and the base station 200 functions as a PDCP entity without limitation. It functions as an upper node provided with. For example, when the

base stations

100 and 200 execute CU-DU splitting, the base station 100 functions as a DU and the base station 200 functions as a CU. When the

base stations

100 and 200 execute multi-RAT dual connectivity (for example, LTE-NR dual connectivity), the base station 100 functions as a secondary base station (SeNB), and the base station 200 is a master base station (MeNB). Function as.

User device 50 can wirelessly communicate with base station 100 and / or 200, and may be any information processing device having a wireless communication function, such as a mobile phone, a smartphone, a tablet, or a wearable device.

Next, a base station 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 5 is a block diagram illustrating a functional configuration of the base station 100 according to an embodiment of the present invention.

As shown in FIG. 5, the base station 100 includes a control unit 110 and a transmission unit 120. For example, the control unit 110 can be realized by a processor, and the transmission unit 120 can be realized by a transmitter.

The control unit 110 determines the state of the base station 100. That is, the control unit 110 monitors the state and / or event of the base station 100 and determines the state and / or event. Specifically, the state or event may be a radio link failure with the user apparatus 50 or a radio link failure detection event. Further, the state or event may be a radio link recovery or radio link recovery detection event with the user apparatus 50. In general, the state and / or event is required to be reliably notified to the base station 200 functioning as an upper node. That is, when the state and / or event notification does not reach the base station 200, the base station 200 loses the opportunity to determine whether to stop or resume data transmission to the base station 100 functioning as a lower node. As a result, data retention in the base station 100, a decrease in throughput of data transmission to the user apparatus 50, and the like occur. For this reason, failure and / or recovery of the radio link is required to be transmitted with relatively high reliability.

The transmission unit 120 transmits information indicating the determined state to the base station 200 a plurality of times. Specifically, the transmission unit 120 repeatedly transmits the control information and / or state information indicating the above-described failure and / or recovery of the radio link to the base station 200 a plurality of times. The number of times of transmission may be the number of times that it can be sufficiently determined that the base station 200 has been reliably reached, may be defined in advance by specifications, or may be specified by the base station 200 functioning as an upper node. Good.

For example, in the NR system, a failure and / or recovery of a radio link is notified in an information element “Cause Value” in DL DATA DELIVERY STATUS (DDDS). The control unit 110 detects a radio link failure and / or recovery between the user apparatus 50 and the base station 100, and the transmission unit 120 repeatedly repeats “Cause Value” indicating the availability of the radio link a plurality of times in the DDDS. 200.

Here, the transmission unit 120 may transmit all or part of the information described above to the base station 200 a plurality of times. For example, the transmission unit 120 may transmit all information elements in the DDDS or some information elements including “Cause Value” to the base station 200 a plurality of times.

For example, the transmission unit 120 may include “Cause Value” indicating a radio link failure (“RADIO LINK OUTAGE”) in each transmission target DDDS as shown in FIG. Good. When receiving the DDDS, as shown in FIG. 6B, the base station 200 functioning as an upper node including the PDCP entity recognizes that traffic transmission between the user apparatus 50 and the base station 100 is unavailable. Can do. On the other hand, as shown in FIG. 6A, the transmission unit 120 may include “Cause Value” indicating radio link recovery (“RADIO LINK RESUME”) in each DDDS to be transmitted during a period in which the radio link is available. Good. When receiving the DDDS, as shown in FIG. 6B, the base station 200 functioning as an upper node including the PDCP entity recognizes that traffic transmission between the user apparatus 50 and the base station 100 is available. Can do.

In one embodiment, the transmission unit 120 may transmit the above-described information to the base station 200 in response to a request from the base station 200. Specifically, as illustrated in FIG. 7A, for each DDDS returned for each “Report polling” that is transmitted a plurality of times, the transmission unit 120 requires information that requires reliability (for example, “Cause Value”). May be included.

In another embodiment, the transmission unit 120 may autonomously transmit the above-described information to the base station 200. For example, when the control unit 110 detects a radio link failure and / or recovery, as illustrated in FIG. 7B, the transmission unit 120 repeatedly repeats DDDS including “Cause Value” indicating the availability of the radio link a plurality of times. May be transmitted autonomously.

According to the above-described embodiment, the upper node can receive the information more reliably only by transmitting the information from the lower node to the upper node a plurality of times. That is, in the procedure for reporting the state of the base station 100 from the lower node to the upper node, it is not necessary to create a new information element and / or a new timer by introduction of delivery confirmation and / or sequence number, and the lower level by a simple mechanism. Information can be reliably transmitted from the node to the upper node.

Note that the block diagram used in the description of the above embodiment shows functional unit blocks. These functional blocks (components) are realized by any combination of hardware and / or software. Further, the means for realizing each functional block is not particularly limited. That is, each functional block may be realized by one device physically and / or logically coupled, and two or more devices physically and / or logically separated may be directly and / or indirectly. (For example, wired and / or wireless) and may be realized by these plural devices.

For example, the user apparatus 50 and the

base stations

100 and 200 in the embodiment of the present invention may function as a computer that performs processing of the wireless communication method of the present invention. FIG. 8 is a block diagram illustrating a hardware configuration of the user apparatus 50 and the

base stations

100 and 200 according to an embodiment of the present invention. The above-described user apparatus 50 and

base stations

100 and 200 are physically configured as computer apparatuses including a processor 1001, a memory 1002, a storage 1003, a communication apparatus 1004, an input apparatus 1005, an output apparatus 1006, a bus 1007, and the like. Also good.

In the following description, the term “apparatus” can be read as a circuit, a device, a unit, or the like. The hardware configurations of the user device 50 and the

base stations

100 and 200 may be configured to include one or a plurality of the devices illustrated in the figure, or may be configured not to include some devices.

The functions of the user apparatus 50 and the

base stations

100 and 200 are such that predetermined processor (program) is read on the hardware such as the processor 1001 and the memory 1002, and the processor 1001 performs computation to perform communication by the communication apparatus 1004. This is realized by controlling data reading and / or writing in the memory 1002 and the storage 1003.

The processor 1001 controls the entire computer by operating an operating system, for example. The processor 1001 may be configured by a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic device, a register, and the like. For example, each component described above may be realized by the processor 1001.

Further, the processor 1001 reads programs (program codes), software modules, and data from the storage 1003 and / or the communication device 1004 to the memory 1002, and executes various processes according to these. As the program, a program that causes a computer to execute at least a part of the operations described in the above embodiments is used. For example, the processing by each component of the user apparatus 50 and the

base stations

100 and 200 may be realized by a control program stored in the memory 1002 and operated by the processor 1001, and may be realized similarly for other functional blocks. Also good. Although the above-described various processes have been described as being executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. Note that the program may be transmitted from a network via a telecommunication line.

The memory 1002 is a computer-readable recording medium, and includes, for example, at least one of ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), and the like. May be. The memory 1002 may be called a register, a cache, a main memory (main storage device), or the like. The memory 1002 can store a program (program code), a software module, and the like that can be executed to implement the wireless communication method according to the embodiment of the present invention.

The storage 1003 is a computer-readable recording medium such as an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (for example, a compact disk, a digital versatile disk, a Blu-ray). (Registered trademark) disk, smart card, flash memory (for example, card, stick, key drive), floppy (registered trademark) disk, magnetic strip, and the like. The storage 1003 may be referred to as an auxiliary storage device. The storage medium described above may be, for example, a database, server, or other suitable medium including the memory 1002 and / or the storage 1003.

The communication device 1004 is hardware (transmission / reception device) for performing communication between computers via a wired and / or wireless network, and is also referred to as a network device, a network controller, a network card, a communication module, or the like. For example, the above-described components may be realized by the communication device 1004.

The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that accepts an input from the outside. The output device 1006 is an output device (for example, a display, a speaker, an LED lamp, etc.) that performs output to the outside. The input device 1005 and the output device 1006 may have an integrated configuration (for example, a touch panel).

Also, each device such as the processor 1001 and the memory 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured with a single bus or may be configured with different buses between apparatuses.

The user equipment 50 and the

base stations

100 and 200 include a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), an FPGA (Field Programmable Gate Array), and the like. The hardware may be configured, and a part or all of each functional block may be realized by the hardware. For example, the processor 1001 may be implemented by at least one of these hardware.

The notification of information is not limited to the aspect / embodiment described in this specification, and may be performed by other methods. For example, notification of information includes physical layer signaling (for example, DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (for example, RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling), It may be implemented by broadcast information (MIB (Master Information Block), SIB (System Information Block)), other signals, or a combination thereof. Also, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC connection setup (RRC Connection Setup) message, an RRC connection reconfiguration (RRC Connection Reconfiguration) message, or the like.

Each aspect / example described in this specification includes LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4G, 5G, FRA (Future Radio Access), W-CDMA. (Registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, UWB (Ultra-WideBand), The present invention may be applied to a Bluetooth (registered trademark), a system using another appropriate system, and / or a next generation system extended based on the system.

The processing procedures, sequences, flowcharts, and the like of each aspect / example described in this specification may be switched in order as long as there is no contradiction. For example, the methods described herein present the elements of the various steps in an exemplary order and are not limited to the specific order presented.

The specific operation performed by the

base stations

100 and 200 in this specification may be performed by the upper node in some cases. In a network composed of one or more network nodes having a base station, various operations performed for communication with a terminal may be performed by the base station and / or other network nodes other than the base station (for example, Obviously, this can be done by MME or S-GW, but not limited to these. Although the case where there is one network node other than the base station in the above is illustrated, a combination of a plurality of other network nodes (for example, MME and S-GW) may be used.

Information etc. can be output from the upper layer (or lower layer) to the lower layer (or upper layer). Input / output may be performed via a plurality of network nodes.

The input / output information or the like may be stored in a specific location (for example, a memory) or may be managed by a management table. Input / output information and the like can be overwritten, updated, or additionally written. The output information or the like may be deleted. The input information or the like may be transmitted to another device.

The determination may be performed by a value represented by 1 bit (0 or 1), may be performed by a true / false value (Boolean: true or false), or may be performed by comparing numerical values (for example, a predetermined value) Comparison with the value).

Each aspect / example described in this specification may be used alone, in combination, or may be switched according to execution. In addition, notification of predetermined information (for example, notification of being “X”) is not limited to explicitly performed, but is performed implicitly (for example, notification of the predetermined information is not performed). Also good.

Although the present invention has been described in detail above, it will be apparent to those skilled in the art that the present invention is not limited to the embodiments described herein. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

Software, whether it is called software, firmware, middleware, microcode, hardware description language, or other names, instructions, instruction sets, codes, code segments, program codes, programs, subprograms, software modules , Applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, etc. should be interpreted broadly.

Further, software, instructions, etc. may be transmitted / received via a transmission medium. For example, software may use websites, servers, or other devices using wired technology such as coaxial cable, fiber optic cable, twisted pair and digital subscriber line (DSL) and / or wireless technology such as infrared, wireless and microwave. When transmitted from a remote source, these wired and / or wireless technologies are included within the definition of transmission media.

The information, signals, etc. described herein may be represented using any of a variety of different technologies. For example, data, commands, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description are voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, light fields or photons, or any of these May be represented by a combination of

Note that the terms described in this specification and / or terms necessary for understanding this specification may be replaced with terms having the same or similar meaning. For example, the channel and / or symbol may be a signal. The signal may be a message. Further, the component carrier (CC) may be called a carrier frequency, a cell, or the like.

The terms “system” and “network” used in this specification are used interchangeably.

In addition, information, parameters, and the like described in this specification may be represented by absolute values, may be represented by relative values from a predetermined value, or may be represented by other corresponding information. . For example, the radio resource may be indicated by an index.

The names used for the above parameters are not limited in any way. Further, mathematical formulas and the like that use these parameters may differ from those explicitly disclosed herein. Since various channels (eg, PUCCH, PDCCH, etc.) and information elements (eg, TPC, etc.) can be identified by any suitable name, the various names assigned to these various channels and information elements are However, it is not limited.

The base station can accommodate one or a plurality of (for example, three) cells (also called sectors). When the base station accommodates a plurality of cells, the entire coverage area of the base station can be divided into a plurality of smaller areas, and each smaller area can be divided into a base station subsystem (for example, an indoor small base station RRH: Remote). A communication service can also be provided by Radio Head). The term “cell” or “sector” refers to part or all of the coverage area of a base station and / or base station subsystem that provides communication services in this coverage. Further, the terms “base station”, “eNB”, “cell”, and “sector” may be used interchangeably herein. A base station may also be called in terms such as a fixed station (fixed station), a NodeB, an eNodeB (eNB), an access point (access point), a femto cell, and a small cell.

A mobile station is defined by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless It may also be called terminal, remote terminal, handset, user agent, mobile client, client, or some other appropriate terminology.

As used herein, the terms “determining” and “determining” may encompass a wide variety of actions. “Judgment”, “decision” can be, for example, calculating, computing, processing, deriving, investigating, looking up (eg, table, database or another (Searching in the data structure), and confirming (ascertaining) what has been confirmed may be considered as “determining” or “determining”. In addition, “determination” and “determination” include receiving (for example, receiving information), transmitting (for example, transmitting information), input (input), output (output), and access. (accessing) (e.g., accessing data in a memory) may be considered as "determined" or "determined". In addition, “determination” and “decision” means that “resolving”, “selecting”, “choosing”, “establishing”, and “comparing” are regarded as “determining” and “deciding”. May be included. In other words, “determination” and “determination” may include considering some operation as “determination” and “determination”.

The terms “connected”, “coupled”, or any variation thereof, means any direct or indirect connection or coupling between two or more elements and It can include the presence of one or more intermediate elements between two “connected” or “coupled” elements. The coupling or connection between the elements may be physical, logical, or a combination thereof. As used herein, the two elements are radio frequency by using one or more wires, cables and / or printed electrical connections, and as some non-limiting and non-inclusive examples By using electromagnetic energy, such as electromagnetic energy having a wavelength in the region, microwave region, and light (both visible and invisible) region, it can be considered to be “connected” or “coupled” to each other.

The reference signal may be abbreviated as RS (Reference Signal), and may be referred to as a pilot depending on an applied standard.

As used herein, the phrase “based on” does not mean “based only on”, unless expressly specified otherwise. In other words, the phrase “based on” means both “based only on” and “based at least on.”

Any reference to elements using designations such as “first”, “second”, etc. as used herein does not generally limit the amount or order of those elements. These designations can be used herein as a convenient way to distinguish between two or more elements. Thus, a reference to the first and second elements does not mean that only two elements can be employed there, or that in some way the first element must precede the second element.

“Means” in the configuration of each apparatus may be replaced with “unit”, “circuit”, “device”, and the like.

As long as the terms “including”, “comprising”, and variations thereof are used herein or in the claims, these terms are inclusive of the term “comprising”. Intended to be Furthermore, the term “or” as used herein or in the claims is not intended to be an exclusive OR.

The radio frame may be composed of one or a plurality of frames in the time domain. Each frame or frames in the time domain may be referred to as a subframe. A subframe may further be composed of one or more slots in the time domain. A slot may further be composed of one or more symbols (OFDM symbols, SC-FDMA symbols, etc.) in the time domain. Each of the radio frame, subframe, slot, and symbol represents a time unit for transmitting a signal. Radio frames, subframes, slots, and symbols may be called differently corresponding to each. For example, in the LTE system, the base station performs scheduling for allocating radio resources (frequency bandwidth, transmission power, etc. that can be used in each mobile station) to each mobile station. The minimum time unit for scheduling may be called TTI (Transmission Time Interval). For example, one subframe may be called a TTI, a plurality of consecutive subframes may be called a TTI, and one slot may be called a TTI. A resource block (RB) is a resource allocation unit in the time domain and the frequency domain, and may include one or a plurality of continuous subcarriers in the frequency domain. In the time domain of the resource block, one or a plurality of symbols may be included, and one slot, one subframe, or a length of 1 TTI may be included. One TTI and one subframe may each be composed of one or a plurality of resource blocks. The structure of the radio frame described above is merely an example, and the number of subframes included in the radio frame, the number of slots included in the subframe, the number of symbols and resource blocks included in the slots, and the subframes included in the resource block The number of carriers can be variously changed.

As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the specific embodiment mentioned above, In the range of the summary of this invention described in the claim, various deformation | transformation・ Change is possible.

10 wireless communication system 50

user equipment

100, 200 base station 110 control unit 120 transmission unit

Claims

A base station,
A control unit for determining the state of the base station;
A transmitter that transmits information indicating the determined state to other base stations a plurality of times;
Base station with
The base station according to claim 1, wherein the transmission unit transmits the information to the other base station in response to a request from the other base station.
The base station according to claim 1 or 2, wherein the transmission unit autonomously transmits the information to the other base station.
The base station according to any one of claims 1 to 3, wherein the base station and the other base station cooperate for wireless communication with a user apparatus.
The base station according to any one of claims 1 to 4, wherein the information indicates availability of a radio link with a user apparatus.