JP7443367B2 - Terminal and communication node - Google Patents

Description

The present invention relates to a terminal and a communication node that perform processing at the layer 2 level of a wireless communication protocol.

The 3rd Generation Partnership Project (3GPP) has specified Long Term Evolution (LTE) and LTE-Advanced (hereinafter referred to as LTE including LTE-Advanced) with the aim of further increasing the speed of LTE. In addition, 3GPP is also considering specifications for a successor system to LTE called 5G or New Radio (NR).

In NR, a layer 2 level buffer (hereinafter referred to as layer 2 buffer) including a packet data convergence protocol (PDCP) layer and a radio link control (RLC) layer is provided in a terminal (Non-patent Document 1). reference).

The layer 2 buffer stores downlink data (DL data) transmitted from the communication node and uplink data (UL data) transmitted to the communication node using the radio bearer configured between the terminal and the communication node. data) are temporarily stored.

The communication node estimates the amount of DL data remaining in the layer 2 buffer of the terminal based on the amount of DL data for which delivery confirmation has not been received among the DL data transmitted to the terminal.

The communication node estimates the amount of UL data remaining in the layer 2 buffer of the terminal based on the buffer status report (BSR) sent from the terminal.

If the communication node determines that there is a possibility that an overflow will occur in the layer 2 buffer of the terminal based on the accumulated amount of DL data and UL data on the terminal side (hereinafter referred to as the accumulated data amount), the communication node will not transmit new data. Stop.

Furthermore, NR defines dual connectivity (DC) in which a terminal communicates using radio resources provided by multiple communication nodes.

In the DC, each communication node can estimate the amount of retained data in the radio bearer set between the terminal and the communication node using the method described above.

TS38.306 V15.6.0 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; User Equipment (UE) radio access capabilities (Release 15), 3GPP, June 2019

However, in the DC, each communication node cannot grasp the amount of retained data in the radio bearer set between the terminal and other communication nodes.

In this way, since the communication node cannot grasp the total amount of accumulated data in all the radio bearers used for the DC, there is a possibility that a large amount of new data will be transmitted to the terminal.

In this case, overflow may occur in the layer 2 buffer of the terminal.

Therefore, the present invention was made in view of the above situation, and when a terminal communicates using radio resources provided by a plurality of communication nodes, an overflow occurs in the layer 2 level buffer of the terminal. The purpose of the present invention is to provide a terminal and a communication node that can reliably prevent the occurrence of

A terminal (200) according to one aspect of the present invention communicates using a plurality of radio bearers (1, 2) set up between the terminal (200) and a plurality of communication nodes (100a, 100b). a transmitter (210) that transmits information indicating a retention state of all data retained in a buffer (240) for storing uplink data and downlink data to each of the plurality of communication nodes (100a, 100b); The control unit (250) causes the transmission unit (210) to transmit information indicating the retention state based on a trigger.

A communication node (100a) according to one aspect of the present invention provides uplink data and downlink data communicated using a radio bearer (1) set between a terminal (200) and the communication node (100a). a transmission unit (110) that transmits information indicating the retention state of data retained in the buffer (240) of the terminal (200) that stores the data to another communication node (100b); and a control section (150) that causes the transmitting section (110) to transmit information indicating the state.

FIG. 1 is an overall schematic configuration diagram of a wireless communication system 10. FIG. 2A is a diagram illustrating a radio bearer set up between the communication node 100a and the terminal 200. FIG. 2B is a diagram illustrating a radio bearer set up between the communication node 100b and the terminal 200. FIG. 3 is a diagram illustrating the layer 2 buffer 240. FIG. 4 is a functional block configuration diagram of communication nodes 100a and 100b. FIG. 5 is a functional block configuration diagram of the terminal 200. FIG. 6 is a diagram showing an example of a sequence of procedures for transmitting retention information by the communication nodes 100a, 100b and the terminal 200. FIG. 7 is a diagram illustrating an example of the operational flow of the retention information transmission process by the terminal 200. FIG. 8 is a diagram showing an example of a sequence of procedures for transmitting retained information by the communication nodes 100a and 100b. FIG. 9 is a diagram illustrating an example of the operational flow of the retention information transmission process by the communication node 100a. FIG. 10 is a diagram illustrating a modification of retention information. FIG. 11 is a diagram showing an example of the hardware configuration of the communication nodes 100a, 100b and the terminal 200.

Hereinafter, embodiments will be described based on the drawings. Note that the same functions and configurations are given the same or similar symbols, and the description thereof will be omitted as appropriate.

(1) Overall schematic configuration of wireless communication system As shown in FIG. 1, the wireless communication system 10 includes a Next Generation-Radio Access Network 20 (hereinafter referred to as NG-RAN 20) and a terminal 200. Note that the terminal is also called user equipment (UE).

NG-RAN20 includes communication nodes 100a and 100b. Note that the specific configuration of the wireless communication system 10, including the number of communication nodes and terminals, is not limited to the example shown in FIG. 1.

NG-RAN 20 actually includes a plurality of NG-RAN Nodes, specifically gNB (or ng-eNB), and is connected to a core network (5GC, not shown) according to NR. Note that NG-RAN20 and 5GC may be simply expressed as "networks".

Each of the communication nodes 100a and 100b is a gNB or ng-eNB. The communication nodes 100a, 100b perform wireless communication according to NR between the communication nodes 100a, 100b and the terminal 200.

The communication nodes 100a, 100b and the terminal 200 use Massive MIMO, which generates a highly directional beam by controlling radio signals transmitted from multiple antenna elements, and carrier aggregation (using multiple component carriers (CC)). CA), and dual connectivity (DC) that simultaneously transmits CC between multiple NG-RAN nodes and terminals. Note that CC is also called a carrier.

The wireless communication system 10 may include an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) instead of the NG-RAN 20. In this case, the E-UTRAN includes multiple E-UTRAN Nodes, specifically eNBs (or en-gNBs), and is connected to a core network (EPC) according to LTE. In this case, each of communication nodes 100a and 100b is an eNB or en-gNB.

In NR, serving cells are classified as follows. Note that the serving cell is a cell in which a wireless link is established between the terminal and the cell.

A group of serving cells associated with a communication node (master node, MN) that provides a control plane connected to the core network is called a master cell group (MCG). The MCG is composed of a primary cell (hereinafter referred to as PCell) and one or more secondary cells (hereinafter referred to as SCell). A PCell is a cell used by a terminal to initiate an initial connection with an MN. Note that the MCG may be configured only with PCells.

A group of serving cells associated with a communication node (secondary node, SN) that does not provide a control plane connected to the core network and provides additional resources to terminals is called a secondary cell group (SCG). . The SCG is composed of a primary SCell (hereinafter referred to as PSCell) and one or more SCells. A PSCell is a cell used by a terminal to initiate an initial connection with an SN. Note that the SCG may be composed of only PSCells.

Note that PCell is also called a special cell (SpCell) in MCG. PSCell is also called SpCell in SCG.

In this embodiment, the communication node 100a is an MN, and the communication node 100b is an SN. Note that the communication node 100b may be an MN, and the communication node 100a may be an SN.

NR defines dual connectivity (DC) in which terminal 200 communicates using radio resources provided by communication nodes 100a and 100b.

FIG. 2A is a diagram illustrating a radio bearer set up between the communication node 100a and the terminal 200 in the DC. As shown in FIG. 2A, a radio bearer 1 is established between the communication node 100a and the terminal 200. Radio bearer 1 is, for example, a signaling radio bearer (SRB) for control plane. Note that when the radio communication system 10 includes E-UTRAN, the radio bearer 1 may be a radio bearer for Voice over LTE (VoLTE).

The protocol stack for the control plane consists of upper layers (Radio Resource Control (RRC) layer), Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Media Access Control (MAC) layer, and physical (PHY) layer (see Figure 2A).

In radio bearer 1, data is transmitted using radio resources of communication node 100a (MN). Note that the radio bearer 1 may be a data radio bearer (DRB) for user plane.

FIG. 2B is a diagram illustrating a radio bearer set between the communication node 100b and the terminal 200 in the DC. As shown in FIG. 2B, a radio bearer 2 is established between the communication node 100b and the terminal 200.

In this embodiment, the radio bearer 2 constitutes a split bearer. Specifically, in layers below the PDCP layer (RLC layer, MAC layer, and PHY layer), data is transmitted using the radio resources of the communication node 100a (MN) and the radio resources of the communication node 100b (SN). transmitted.

The radio bearer 2 includes a primary path 2a that transmits data using the radio resources of the communication node 100b, and a secondary path 2b that transmits data using the radio resources of the communication node 100a.

The primary path 2a and the secondary path 2b are branched at the PDCP layer of the communication node 100b. Therefore, terminal 200 manages radio bearer 2 as a radio bearer set between terminal 200 and communication node 100b.

Note that the primary path 2a and the secondary path 2b may be branched at the PDCP layer of the communication node 100a. In this case, terminal 200 manages radio bearer 2 as a radio bearer set between terminal 200 and communication node 100a.

The protocol stack for the user plane is composed of an upper layer (Service Data Adaptation Protocol (SDAP)), a PDCP layer, an RLC layer, a MAC layer, and a PHY layer (see FIG. 2B).

Each of the control plane protocol stack and the user plane protocol stack is classified into layers 1 to 3. Layer 1 includes a PHY layer and is also called a lower layer. Layer 2 includes a MAC layer, an RLC layer, and a PDCP layer. Layer 3 includes an RRC layer or an SDAP layer, and is also called an upper layer.

Note that the classification of protocol stacks is not limited to this. For example, layer 2 may include only an RLC layer and a PDCP layer. Furthermore, with the target layer as a reference, a layer located at an upper level may be referred to as an upper layer, and a layer located at a lower level may be referred to as a lower layer.

The terminal 200 includes a layer 2 buffer 240, as described later. Layer 2 buffer 240 is a layer 2 buffer, and is used by terminal 200 to perform layer 2 level processing.

FIG. 3 is a diagram illustrating the layer 2 buffer 240. As shown in FIG. 3, the layer 2 buffer 240 is logically divided into an uplink (UL) data storage section 241 and a downlink (DL) data storage section 243.

The UL data storage unit 241 temporarily stores UL data transmitted from the terminal 200 to the communication nodes 100a and 100b. Examples of the UL data temporarily stored in the UL data storage section 241 include the following data.

・UL data before transmission processing is performed at the PDCP layer ・UL data for which transmission processing is performed at the PDCP layer ・After transmission processing is performed at the PDCP layer, an acknowledgment (ACK) is received from the RLC layer In this embodiment, the UL data storage unit 241 stores UL data for each radio bearer. ing. Specifically, UL data communicated by radio bearer 1 is stored in area 241a. UL data communicated by radio bearer 2 is stored in area 241b.

Note that in the UL data storage unit 241, if the UL data is associated with the radio bearer to which the UL data is transmitted, the UL data does not need to be stored for each radio bearer.

With such a configuration, the terminal 200 can acquire the retention state of UL data stored in the layer 2 buffer 240 for each radio bearer.

Before the terminal 200 transmits a buffer status report (BSR) to a communication node, the terminal 200 stores the buffer status report (BSR) in an area in the UL data storage unit 241 corresponding to the radio bearer set between the terminal 200 and the communication node. Obtain the amount of accumulated UL data. The terminal 200 transmits the obtained accumulated amount of UL data to the communication node using the BSR.

Upon receiving the BSR from the terminal 200, the communication node transmits a UL grant to the terminal 200 and allocates radio resources for UL data transmission. Upon receiving the UL grant, the terminal 200 can transmit UL data to the communication node using the allocated radio resources. Therefore, in the case of UL data transmission based on grant assignment, it is essential to store the UL data before transmission processing is performed in the PDCP layer.

DL data storage section 243 temporarily stores DL data transmitted from communication nodes 100a and 100b to terminal 200. Examples of DL data temporarily stored in the DL data storage unit include the following data.

・DL data received from the MAC layer and before receiving processing is performed at the RLC layer ・DL data received from the MAC layer and receiving processing performed at the RLC layer ・DL data received from the MAC layer, and , DL data after reception processing is performed at the RLC layer but before reception processing is performed at the PDCP layer ・DL data received from the MAC layer and received at the PDCP layer after reception processing is performed at the RLC layer DL data undergoing processing (including reordering processing) In this embodiment, the DL data storage unit 243 stores DL data for each radio bearer. Specifically, DL data communicated by radio bearer 1 is stored in area 243a. DL data communicated by radio bearer 2 is stored in area 243b.

Note that in the DL data storage unit 243, if the DL data is associated with the radio bearer to which the DL data is transmitted, the DL data does not need to be stored for each radio bearer.

With such a configuration, the terminal 200 can acquire the retention state of DL data stored in the layer 2 buffer 240 for each radio bearer.

Note that in this embodiment, the sizes of areas 241a and 241b in the UL data storage unit 241 and areas 243a and 243b in the DL data storage unit 243 are not fixed, and the sizes of the areas 241a and 241b in the UL data storage unit 241 and the areas 243a and 243b in the DL data storage unit 243 are not fixed. It can vary dynamically depending on the amount of data retained.

Therefore, in the present embodiment, the communication node 100a uses the amount of data that remains in the layer 2 buffer 240 rather than the amount of data that remains in the areas 241a and 243a where UL data and DL data communicated by radio bearer 1 are stored. Transmission control is performed based on the total amount of accumulated data. Similarly, the communication node 100b uses the total amount of data stored in the layer 2 buffer 240, not the amount of data stored in the areas 241b and 243b where UL data and DL data communicated by radio bearer 2 are stored. Transmission control is performed based on.

When an overflow occurs in the layer 2 buffer 240, the terminal 200 performs the following operations, for example.

・Discard all the data remaining in the layer 2 buffer. ・Discard the data remaining in the layer 2 buffer to the extent that the overflow in the layer 2 buffer is resolved. ・Remove UL data to the layer 2 buffer. As described later, each of the communication nodes 100a and 100b stores data in the layer 2 buffer 240 without forwarding it, which is communicated using radio bearers 1 and 2 used for DC. The terminal 200 performs transmission control based on the status of the terminal 200.

(2) Functional block configuration of wireless communication system Next, the functional block configuration of the wireless communication system 10 will be explained. Specifically, the functional block configurations of communication nodes 100a, 100b and terminal 200 will be described. Hereinafter, only portions related to the features of this embodiment will be described. Therefore, it goes without saying that the communication nodes 100a, 100b and the terminal 200 include other functional blocks that are not directly related to the features of this embodiment.

FIG. 4 is a functional block configuration diagram of communication nodes 100a and 100b. Note that since communication nodes 100a and 100b have the same configuration, a description of communication node 100b will be omitted. As shown in FIG. 4, the communication node 100a includes a transmitter 110, a receiver 120, a timer 130, a manager 140, and a controller 150.

The transmitter 110 transmits DL data using the radio bearer 1 set up between the communication node 100a and the terminal 200. For example, transmitting section 110 transmits new DL data to terminal 200 based on transmission control by control section 150.

The transmitter 110 of the communication node 100a determines whether the data communicated by the radio bearer 1 is accumulated in the layer 2 buffer 240 in "transmission procedure of accumulated information between communication nodes 100a and 100b" (see FIG. 8), which will be described later. Retention information indicating the current status is transmitted to the communication node 100b. Similarly, the transmitting unit 110 of the communication node 100b transmits data communicated by radio bearer 2 to the layer 2 buffer in "procedure for transmitting retention information between communication nodes 100a and 100b" (see FIG. 8), which will be described later. 240 is transmitted to the communication node 100a.

The receiving unit 120 receives the UL data using the radio bearer 1 set up between the communication node 100a and the terminal 200. For example, receiving section 120 receives BSR from terminal 200.

The receiving unit 120 determines whether data communicated by radio bearers 1 and 2 is retained in the layer 2 buffer 240 in the "procedure for transmitting retained information between the communication node 100a and the terminal 200" (see FIG. 6), which will be described later. The terminal 200 receives retention information indicating the status of the terminal 200.

The receiving unit 120 indicates a state in which data communicated by radio bearer 2 is retained in the layer 2 buffer 240 in the "procedure for transmitting retained information between communication nodes 100a and 100b" (see FIG. 8), which will be described later. Retention information is received from communication node 100b.

The timer 130 is used to determine whether or not to transmit the retention information when transmitting the retention information periodically.

The management unit 140 manages the retention information received from the terminal 200 in association with the radio bearers 1 and 2 in the "procedure for transmitting retention information between the communication node 100a and the terminal 200" (see FIG. 6), which will be described later. do.

The management unit 140 manages the retention information estimated by the communication node 100a in association with the radio bearer 1 in the "procedure for transmitting retention information between communication nodes 100a and 100b" (see FIG. 8), which will be described later. The retention information received from the communication node 100b is managed in association with the radio bearer 2.

The control unit 150 performs processing at the layer 2 level.

The control unit 150 controls the transmission of new DL data based on the retention information acquired from the terminal 200 in the "transmission procedure of retention information between the communication node 100a and the terminal 200" (see FIG. 6), which will be described later. I do.

The control unit 150 indicates a state in which data communicated by radio bearer 1 is retained in the layer 2 buffer 240 in a "procedure for transmitting retained information between communication nodes 100a and 100b" (see FIG. 8), which will be described later. Estimate retention information. Control unit 150 instructs transmitter 110 to transmit the estimated retention information to communication node 100b based on a specific trigger.

The control unit 150 performs a transmission process based on the retention information estimated by the control unit 150 and the retention information acquired from the communication node 100b in the “procedure for transmitting retention information between communication nodes 100a and 100b” (see FIG. 8), which will be described later. control the transmission of new DL data.

If the control unit 150 uses the timer 130 to determine that a predetermined period of time has passed since the transmission of the retention information, it instructs the transmission unit 110 to transmit new retention information to the communication node 100b.

When performing transmission control, the control unit 150 acquires retention information associated with each radio bearer from the management unit 140.

FIG. 5 is a functional block configuration diagram of the terminal 200. As shown in FIG. 5, the terminal 200 includes a transmitter 210, a receiver 220, a timer 230, a layer 2 buffer 240, and a controller 250.

The transmitter 210 transmits UL data using the radio bearer 1 set up between the communication node 100a and the terminal 200. The transmitter 210 transmits UL data using the radio bearer 2 set up between the communication node 100b and the terminal 200. For example, the transmitter 210 transmits the BSR to the communication nodes 100a and 100b.

The transmitting unit 210 determines whether data communicated by radio bearers 1 and 2 is retained in the layer 2 buffer 240 in "procedure for transmitting retained information between the communication node 100a and the terminal 200" (see FIG. 6), which will be described later. The communication node 100a, 100b transmits retention information indicating the status of the communication node 100a, 100b.

The receiving unit 220 receives the DL data using the radio bearer 1 set up between the communication node 100a and the terminal 200. The transmitter 210 receives the DL data using the radio bearer 2 set up between the communication node 100b and the terminal 200. For example, the receiving unit 220 receives new DL data from the communication nodes 100a, 100b based on transmission control by the communication nodes 100a, 100b.

The timer 230 is used to determine whether or not to transmit the retention information when transmitting the retention information periodically.

As described above, the layer 2 buffer 240 temporarily stores UL data and DL data for each radio bearer.

The control unit 250 performs processing at the layer 2 level.

The control unit 250 determines whether data communicated by radio bearers 1 and 2 is retained in the layer 2 buffer 240 in "procedure for transmitting retained information between the communication node 100a and the terminal 200" (see FIG. 6), which will be described later. Acquire retention information indicating the status of Control unit 250 instructs transmitting unit 210 to transmit the acquired retention information to communication nodes 100a and 100b based on a specific trigger.

The control unit 250 instructs the transmitting unit 210 to transmit retention information indicating that data communicated by radio bearer 1 is retained in the layer 2 buffer 240 to the communication node 100a using BSR. Similarly, the control unit 250 instructs the transmitting unit 210 to transmit retention information indicating that data communicated by radio bearer 2 is retained in the layer 2 buffer 240 to the communication node 100b using BSR. Instruct.

If the control unit 250 uses the timer 230 to determine that a predetermined period of time has passed since the transmission of the retention information, it instructs the transmission unit 210 to transmit new retention information to the communication nodes 100a, 100b.

(3) Operation of wireless communication system Next, the operation of the wireless communication system 10 will be explained. As described above, in the DC, data communicated by radio bearers 1 and 2 is temporarily stored in the layer 2 buffer 240 of the terminal 200. This state can also be expressed as data communicated by radio bearers 1 and 2 remaining in the layer 2 buffer 240.

In this embodiment, as an operation of the wireless communication system 10, each of the communication nodes 100a and 100b in the DC grasps the state in which data communicated by radio bearers 1 and 2 is retained in the layer 2 buffer 240. , the operation of controlling transmission to the terminal 200 will be explained.

(3.1) Reporting of retention information between the terminal and the communication node First, the terminal 200 reports to each of the communication nodes 100a and 100b that the data communicated by radio bearers 1 and 2 is stored in the layer 2 buffer 240. A case will be explained in which the retention information indicating the status of retention is reported.

(3.1.1) Retention Information As described above, the layer 2 buffer 240 is logically divided into the UL data storage section 241 and the DL data storage section 243 (see FIG. 3). In this case, the retention information includes, for example, the following information.

・The sum of the total amount of UL data stored in the UL data storage unit 241 and the total amount of DL data stored in the DL data storage unit 243 (hereinafter referred to as the total amount of stored data)
- Ratio of the total amount of accumulated data to the total capacity of data that can be stored in the UL data storage section 241 and DL data storage section 243 (hereinafter referred to as total buffer size) - UL data storage section 241 and DL data storage section 243 free space (hereinafter referred to as free space of all buffers)
- Total amount of retained data and total buffer size - A flag indicating whether the terminal 200 is able to receive new data In this way, in this case, the terminal 200 uses all the radio bearers 1 and 2 used for DC , and transmits retention information indicating the retention status of all data retained in the layer 2 buffer 240 to each communication node.

(3.1.2) Procedure for transmitting retained information Next, a procedure for transmitting retained information between the communication nodes 100a, 100b and the terminal 200 will be explained. FIG. 6 is a diagram showing an example of a sequence of procedures for transmitting retention information by the communication nodes 100a, 100b and the terminal 200.

As shown in FIG. 6, when detecting a specific trigger (S11), the terminal 200 transmits retention information indicating the retention status of data retained in the layer 2 buffer 240 in all radio bearers used for the DC. Get (S13).

Examples of specific triggers in S11 include the following events.

- When a message instructing to report retained information is received from the network (for example, communication nodes 100a, 100b) - When a predetermined time has passed since the previous transmission of retained information - When the total amount of retained data exceeds a threshold - All When the amount of retained data exceeds the threshold for a predetermined period of time - When the free space of all buffers falls below the threshold - When the free space of all buffers remains below the threshold for a predetermined period of time - When terminal 200 is present When the serving cell changes - When the PDCP layer on the network side that terminates the radio bearer set between the terminal and the network (for example, communication nodes 100a, 100b) changes - When new data is received, the layer 2. When there is a possibility of overflow occurring in the buffer The above-mentioned retention information report instruction message may be included in an RRC message, a MAC control element (CE), or a layer 1 (L1) signal. The above-mentioned predetermined time and threshold may be set in advance from the network (for example, communication nodes 100a, 100b).

Further, the following event can also be cited as a specific trigger in S11.

・RRC connection setup
・RRC connection resume
・RRC connection suspend
・RRC connection re-establishment
・UE capability inquiry
・Resource block settings (RB setup)
・Resource block modification (RB modification)
・Resource block release (RB release)
・PDCP establishment
・PDCP re-establishment
・PDCP data recovery
・PDCP On Discard (PDCPOnDiscard)
・PDCP release
・PDCP status report
・RLC establishment
・RLC re-establishment
・RLC release
・Logical channel (LCH) establishment
・LCH release
・MAC reset
・ReconfigurationWithsync in procedures such as handover, SCG change, cell change, etc.
・Changing bearer type ・Configuring CA or multi-radio (MR) DC ・Deleting CA or MR-DC The network (for example, communication nodes 100a, 100b) receives one or more of the multiple events listed above. , radio bearer unit, RLC bearer unit, RLC channel unit, LCH unit, quality of service (QoS) unit, or a unit in which some of these units are grouped in advance in the terminal 200. It's okay. In this case, the terminal 200 may transmit the acquired retention information to the communication nodes 100a and 100b when detecting at least one event among preset events.

The network (e.g., communication nodes 100a, 100b) processes two or more of the above-mentioned events on a radio bearer basis, RLC bearer basis, RLC channel basis, LCH basis, and quality of service (QoS). ) unit, or a unit in which some of these units are grouped may be set in advance in the terminal 200. In this case, the terminal 200 may transmit the obtained retention information to the communication nodes 100a and 100b when all preset events are detected.

Upon acquiring the retention information based on the detection of a specific trigger, the terminal 200 transmits the acquired retention information to the communication nodes 100a and 100b (S15). The terminal 200 may include the retention information in an RRC message, MAC CE, or L1 signal and transmit it to the communication nodes 100a, 100b. The terminal 200 may include the retention information in a PDCP control protocol data unit (PDU) such as a PDCP status report and transmit it to the communication nodes 100a and 100b.

The terminal 200 transmits retention information in units of radio bearers, RLC bearers, RLC channels, LCHs, quality of service (QoS), or a grouping of some of these units. You may.

Upon receiving the retention information from the terminal 200, each of the communication nodes 100a and 100b performs transmission control on the terminal 200 (S17). Specifically, when each of the communication nodes 100a and 100b transmits new DL data based on the retention information received from the terminal 200, there is a possibility that an overflow will occur in the layer 2 buffer 240 of the terminal 200. Determine whether or not.

If there is no possibility of overflow occurring, each of communication nodes 100a and 100b transmits new DL data to terminal 200. On the other hand, if there is a possibility that overflow will occur, each of the communication nodes 100a and 100b stops transmitting new DL data to the terminal 200.

For example, if the total received data amount or the ratio of the total received data amount to the total received buffer size exceeds a threshold, each communication node 100a, 100b sends new DL data to the terminal 200. Stop sending. Further, if the free capacity of all received buffers is less than the threshold, each of the communication nodes 100a and 100b stops transmitting new DL data to the terminal 200. Further, if the received flag indicates that new data cannot be received, each of the communication nodes 100a and 100b stops transmitting new DL data to the terminal 200.

(3.1.3) Retention Information Transmission Process Next, an example of retention information transmission processing by the terminal 200 will be described. FIG. 7 is a diagram illustrating an example of the operational flow of the retention information transmission process by the terminal 200.

As shown in FIG. 7, when the terminal 200 acquires the retention information based on the detection of a specific trigger, it transmits the retention information to the communication nodes 100a and 100b (S21). After transmitting the retention information, the terminal 200 determines whether a predetermined time has elapsed since the transmission of the retention information (S23).

When determining that the predetermined time has elapsed, the terminal 200 acquires new retention information and transmits the new retention information to the communication nodes 100a and 100b (S25). On the other hand, if the terminal 200 determines that the predetermined time has not elapsed, it waits until the predetermined time has elapsed.

After transmitting the new retention information, the terminal 200 determines whether to end the transmission of retention information (S27). If the transmission of the retention information is not finished, the operation of the terminal 200 returns to S23. On the other hand, when ending the transmission of the retention information, the terminal 200 ends the transmission of the retention information.

In this way, the terminal 200 transmits retention information to the communication nodes 100a and 100b at predetermined intervals.

(3.2) Report of retention information between communication nodes Next, the communication node 100a estimates retention information indicating that data communicated by radio bearer 1 is retained in the layer 2 buffer 240, and estimates A case will be described in which the acquired retention information is reported to the communication node 100b. In this case, although the explanation is omitted, the communication node 100b similarly estimates the retention information indicating the state in which the data communicated by radio bearer 2 is retained in the layer 2 buffer 240. The retention information is reported to the communication node 100a.

(3.2.1) Retention Information In this case, the following information is listed as the retention information that the communication node 100a reports to the communication node 100b, for example.

・The sum of the amount of UL data stored in the area 241a of the UL data storage unit 241 and the amount of DL data stored in the area 243a of the DL data storage unit 243 (hereinafter referred to as the amount of stored data)
・Ratio of the amount of accumulated data to the data capacity that can be stored in the area 241a of the UL data storage unit 241 and the area 243a of the DL data storage unit 243 (hereinafter referred to as buffer size) ・The area 241a of the UL data storage unit 241 and the free capacity of the area 243a of the DL data storage unit 243 (hereinafter referred to as buffer free capacity)
- Amount of accumulated data and buffer size - A flag indicating whether the terminal 200 can receive new data (3.2.3) Estimation of accumulated information at each communication node Next, estimation of accumulated information at the communication node 100a Explain the method.

In the PDCP layer that performs reordering processing, the communication node 100a determines the amount of UL data remaining in the area 241a of the UL data storage unit 241 (hereinafter referred to as the amount of accumulated UL data) based on the BSR transmitted from the terminal 200. ) is estimated.

Note that in radio bearer 2, if the amount of retained UL data is less than a threshold (for example, ul-DataSplitThreshold notified in an RRC message), terminal 200 uses BSR to connect to the communication node to which primary path 2a is set. Send the amount of accumulated UL data to 100b. On the other hand, the terminal 200 uses the BSR to transmit the value 0 to the communication node 100a to which the secondary path 2b is set.

In the PDCP layer that performs the reordering process, the communication node 100a stores the area 243a of the DL data storage unit 243 based on the amount of DL data for which delivery confirmation has not been received in the correct order among the DL data transmitted to the terminal 200. Estimate the amount of DL data that is retained in (hereinafter referred to as the amount of retained DL data).

The communication node 100a estimates retention information based on the amount of retained UL data and the amount of retained DL data. For example, the communication node 100a adds the amount of retained UL data and the amount of retained DL data to estimate the amount of retained data.

With such a method, the communication node 100a can estimate the retention information in the radio bearer 1 set between the terminal 200 and the communication node 100a. Note that in this case, the communication node 100a cannot estimate the retention information in the radio bearer set between the terminal 200 and the communication node 100b.

(3.2.4) Procedure for transmitting retention information Next, a procedure for transmitting retention information between communication nodes 100a and 100b will be explained. FIG. 8 is a diagram showing an example of a sequence of procedures for transmitting retained information by the communication nodes 100a and 100b. Note that in FIG. 8, the communication node 100a transmits retention information to the communication node 100b.

As shown in FIG. 8, when the communication node 100a detects a specific trigger (S31), the communication node 100a detects data retained in the layer 2 buffer 240 in radio bearer 1 of radio bearers 1 and 2 used for DC. Retention information indicating the retention state of is estimated (S33).

Examples of specific triggers in S31 include the following events.

- When a message instructing to report the accumulated information is received from the communication node 100b - When a predetermined time has passed since the previous transmission of accumulated information - When the amount of accumulated data exceeds the threshold - A state where the amount of accumulated data exceeds the threshold continues for a predetermined period of time - When the buffer free space falls below the threshold - When the buffer free space remains below the threshold for a predetermined period of time - When a new communication node is set for the terminal 200 - When information indicating that new data cannot be received is received from the terminal 200 The above-mentioned retention information report instruction message may be included in the Xn signal. Note that when the wireless communication system 10 includes E-UTRAN, the above-described retention information report instruction message may be included in the X2 signal. The above-mentioned predetermined time and threshold may be set in advance from the network (for example, communication node 100b).

The network (for example, the communication node 100b) may preset one or more events among the plurality of events described above in the communication node 100a. In this case, the communication node 100a may transmit the estimated retention information to the communication node 100b when detecting at least one event among preset events.

The network (for example, the communication node 100b) may preset two or more events among the plurality of events described above in the communication node 100a. In this case, the communication node 100a may transmit the estimated retention information to the communication node 100b when all preset events are detected.

When the communication node 100a estimates the retention information based on the detection of a specific trigger, it transmits the acquired retention information to the communication node 100b (S35). The communication node 100a may include it in a data delivery status message (DDDS) and transmit it to the communication node 100b. The communication node 100a collects the UE capabilities of the terminal 200, such as the value of the quality information (e.g., measurement report, channel state information (CSI), power headroom (PHR), etc.) of the radio bearer 1, as well as the UE category, along with the retention information. etc. may be reported.

Note that the communication node 100a may independently transmit the UL retention information estimated based on the amount of retained UL data and the DL retention information estimated based on the amount of retained DL data to the communication node 100b. In this case, for example, the communication node 100b may independently transmit a report instruction message for UL retention information and a report message for DL retention information.

Upon receiving the retention information from the communication node 100a, the communication node 100b performs transmission control on the terminal 200 (S37). Specifically, when the communication node 100b transmits new DL data based on the retention information on the radio bearer 1 received from the communication node 100a and the retention information on the radio bearer 2 estimated by the communication node 100b, , determine whether an overflow is likely to occur in the layer 2 buffer 240 of the terminal 200.

If there is no possibility of overflow occurring, communication node 100b transmits new DL data to terminal 200. On the other hand, if there is a possibility that overflow will occur, communication node 100b stops transmitting new DL data to terminal 200.

The specific determination method is the same as that described in "(3.1.2) Retention information transmission procedure" above.

(3.2.5) Retention Information Transmission Process Next, an example of retention information transmission processing by the communication node 100a will be described. FIG. 9 is a diagram illustrating an example of the operational flow of the retention information transmission process by the communication node 100a.

As shown in FIG. 9, when the communication node 100a estimates the retention information based on the detection of a specific trigger, it transmits the retention information to the communication node 100b (S41). After transmitting the retention information, the communication node 100a determines whether a predetermined time has elapsed since the transmission of the retention information (S43).

When determining that the predetermined time has elapsed, the communication node 100a estimates new retention information and transmits the new retention information to the communication node 100b (S45). On the other hand, if the communication node 100a determines that the predetermined time has not elapsed, it waits until the predetermined time has elapsed.

After transmitting the new retention information, the communication node 100a determines whether to end the transmission of retention information (S47). If the transmission of the retention information is not finished, the operation of the communication node 100a returns to S43. On the other hand, when ending the transmission of the retention information, the communication node 100a ends the transmission of the retention information.

In this way, communication node 100a transmits retention information to communication node 100b at predetermined intervals.

(3.4) Others Next, modified examples will be explained below.

As the retention information used in "(3.1) Report of retention information between terminal and communication node" described above, a state variable of the PDCP layer or RLC layer may be used instead of the data amount. In this case, the terminal 200 may be notified from the network (for example, the communication nodes 100a, 100b) which state variable to use among the PDCP layer state variable and the RLC layer state variable as the retention information.

FIG. 10 is a diagram illustrating a modification of retention information. As shown in FIG. 10, in the terminal 200, four packets remain in the layer 2 buffer 240, specifically, in the area 243a of the DL data storage unit 243.

The packet contains a count value. The count value includes a hyperframe number (HFN) and a PDCP-sequence number (SN). PDCP-SN is incremented on the transmitting side every time a packet is sent from the PDCP layer to the RLC layer. HFN is incremented on the transmitting side every time PDCP-SN goes around.

The PDCP-SNs of the four packets staying in the layer 2 buffer 240 are given values 1 to 4. The value 0 is assigned to the PDCP-SN of the packet finally sent to the upper layer. The PDCP layer sends the PDCP packet to the upper layer using the set RX_DELIV. A value of 5 is assigned to the PDCP-SN of the packet that is expected to be sent to the layer 2 buffer 240 next. The PDCP layer receives the packet using the configured RX_NEXT.

In such a retention state, when the terminal 200 detects a specific trigger, the terminal 200 uses the PDCP-SN of the last packet sent to the upper layer and the PDCP-SN of the packet retained in the layer 2 buffer 240 as retention information. The largest value among the SNs is notified. Specifically, the terminal 200 transmits the PDCP-SN values 0 and 4 as the retention information to the communication node 100a. The communication node 100a estimates that four PDCP packets are retained in the layer 2 buffer 240 based on the received PDCP-SN values 0 and 4.

When the terminal 200 detects a specific trigger, the terminal 200 uses the smallest value of the PDCP-SN of the packets staying in the layer 2 buffer 240 as the staying information, and the next one is expected to be sent to the layer 2 buffer 240. The PDCP-SN of the packet may also be notified. The packet with the lowest value PDCP-SN is then sent to the upper layer. Specifically, the terminal 200 may transmit the PDCP-SN values 1 and 5 as the retention information to the communication node 100a.

The aforementioned packets may be service data units (SDUs) or packet data units (PDUs), for example in the PDCP layer or the RLC layer. The terminal 200 may use PDCP-SN, HFN, count value, etc. instead of PDCP-SN.

Furthermore, the terminal 200 stores, as retention information, the number of PDCP SDUs, PDCP PDUs, RLC SDUs, RLC PDUs, SDPA SDUs, or SDPA PDUs retained in the layer 2 buffer, average data size, maximum data size, minimum data size, Statistical information and the like may be transmitted to communication nodes 100a and 100b.

Similarly, as the retention information used in "(3.2) Report of retention information between communication nodes" described above, the state variable of the PDCP layer or RLC layer described above may be used instead of the data amount. In this case, each communication node transmits, for example, the PDCP-SN of the packet, PDCP-SN and HFN, count value, etc. as retention information to other communication nodes.

The contents of the retention information used in "(3.1) Report of retention information between terminal and communication node" and "(3.2) Report of retention information between communication nodes" described above are set by the network. It's okay.

The retention information used in "(3.1) Report of retention information between terminal and communication node" and "(3.2) Report of retention information between communication nodes" described above is the retention information for UL and It may be divided into DL retention information and transmitted individually.

The retention information used in "(3.1) Report of retention information between a terminal and a communication node" and "(3.2) Report of retention information between communication nodes" described above is divided for each QoS, May be sent individually.

The following information can also be cited as the retention information used in "(3.2) Report of retention information between communication nodes".

-Amount of accumulated data in the target radio bearer for each QoS -Buffer free capacity in the target radio bearer for each QoS -Ratio of the amount of accumulated data in the target radio bearer for each QoS to the buffer size

(4) Effects and Effects According to the embodiment described above, the terminal 200 transmits UL data and DL data that are communicated using the radio bearers 1 and 2 set between the terminal 200 and the communication nodes 100a and 100b. Information indicating the retention status of all data retained in the layer 2 buffer 240 is transmitted to the communication nodes 100a, 100b based on a specific trigger.

With such a configuration, communication nodes 100a and 100b can grasp the total amount of retained data in radio bearers 1 and 2, and therefore can perform appropriate transmission control. Therefore, the terminal 200 can reliably prevent the layer 2 buffer 240 from overflowing.

As described above, when an overflow occurs in the layer 2 buffer 240, data is discarded, specifically, packets are discarded. When packet discard occurs, the following problems are a concern.

・Deterioration of communication quality due to packet loss in User Datagram Protocol (UDP) communication ・Increase in communication delay due to TCP retransmission in Transmission Control Protocol (TCP) communication ・Decrease in throughput due to congestion window reduction in TCP communication - If a part of the packet is discarded, the reordering process does not end and a communication delay occurs until the timer (t-Reordering timer) expires. However, with the above configuration, the terminal 200 Since the occurrence of overflow can be reliably prevented, deterioration of communication quality, occurrence and increase of communication delay, and decrease in throughput can be avoided in the wireless communication system 10.

According to the embodiment described above, the terminal 200 transmits information indicating the retention state to the communication nodes 100a and 100b at regular intervals.

With such a configuration, the communication nodes 100a and 100b can periodically grasp the retention state of data retained in the layer 2 buffer 240, and therefore can perform more appropriate transmission control. Therefore, the terminal 200 can more reliably prevent overflow from occurring in the layer 2 buffer 240.

According to the embodiment described above, the communication node 100a stores the layer 2 buffer 240 of the terminal 200 for storing UL data and DL data communicated using the radio bearer 1 set between the terminal 200 and the communication node 100a. Information indicating the retention state of retained data is transmitted to the communication node 100b based on a specific trigger.

With such a configuration, the communication node 100b can grasp the amount of retained data in the radio bearer 1 set between the communication node 100a and the terminal 200.

Similarly, the communication node 100b stores data accumulated in the layer 2 buffer 240 of the terminal 200 that stores UL data and DL data communicated using the radio bearer 2 set between the terminal 200 and the communication node 100b. Information indicating the state is transmitted to the communication node 100a based on a specific trigger.

With such a configuration, the communication node 100a can grasp the amount of retained data in the radio bearer 2 set between the communication node 100b and the terminal 200.

In this way, the communication nodes 100a and 100b can grasp the total amount of retained data in the radio bearers 1 and 2, and therefore can perform appropriate transmission control. Therefore, communication nodes 100a and 100b can reliably prevent overflow from occurring in layer 2 buffer 240 of terminal 200.

According to the embodiment described above, the communication node 100a transmits information indicating the retention state to the communication node 100b at regular intervals. Similarly, the communication node 100b transmits information indicating the retention state to the communication node 100a at regular intervals.

With such a configuration, the communication nodes 100a and 100b can periodically grasp the retention state of data retained in the layer 2 buffer 240, and therefore can perform more appropriate transmission control. Therefore, communication nodes 100a and 100b can more reliably prevent overflow from occurring in layer 2 buffer 240 of terminal 200.

(5) Other Embodiments Although the content of the present invention has been explained above in accordance with the embodiments, it is understood that the present invention is not limited to these descriptions and that various modifications and improvements are possible. It is self-evident to business operators.

In the embodiment described above, the terminal 200 is provided with the layer 2 buffer 240 including the UL data storage section 241 and the DL data storage section 243, but the configuration of the layer 2 buffer is not limited to this. For example, instead of the layer 2 buffer 240, a layer 2 buffer for UL data and a layer 2 buffer for DL data may be provided separately.

In this case, each of the communication nodes 100a and 100b knows that the DL data communicated by all the radio bearers 1 and 2 used for the DC is temporarily stored in the layer 2 buffer for DL data. , may perform transmission control on the terminal 200.

In the embodiment described above, the terminal 200 communicates using the radio resources provided by the communication nodes 100a and 100b, but the number of communication nodes is not limited to this. For example, terminal 200 may communicate using radio resources provided by three or more communication nodes.

In this case, when reporting retention information between communication nodes, each communication node transmits retention information to two other communication nodes.

In the embodiment described above, the retention information is reported between the communication nodes 100a and 100b, but the reporting of retention information between the communication nodes is not limited to this. For example, when a communication node is functionally separated into an aggregation node (CU) and a distributed node (DU), retention information may be reported between the CU and DU via the F1 interface.

If the communication node's CU is functionally separated into a CU-CP that terminates the control plane and a CU-UP that terminates the user plane, stagnation occurs between the CU-CP and CU-UP via the E1 interface. Information may be reported.

In the embodiment described above, when the terminal 200 communicates using radio resources provided by a plurality of communication nodes, the retention information may be collected in any communication node among the plurality of communication nodes. .

In the embodiment described above, the terminal 200 may individually transmit retention information for each layer. Furthermore, the terminal 200 may transmit the retention information of multiple layers at once. Layers to be transmitted may be limited to layers having a buffer function (for example, a PDCP layer and an RLC layer).

In the embodiment described above, if the terminal 200 is equipped with another buffer (for example, a MAC buffer) in addition to the layer 2 buffer, the amount of data remaining in the other buffer is calculated as the total amount of data remaining in the layer 2 buffer. It may or may not be added to the data amount. In this case, the terminal 200 may notify the communication nodes 100a, 100b as to whether or not to add the amount of data remaining in other buffers to the total amount of data remaining in the layer 2 buffer.

In the embodiments described above, the data granularity and precision (for example, bytes, kilobytes, megabytes, or an indicator indicating the amount of data) in the transmission of retention information by the terminal 200 may differ depending on the layer to be transmitted. . In this case, the granularity and precision of the data may be specified by the network.

In the embodiments described above, the network (for example, the communication nodes 100a, 100b) may hold information regarding whether the terminal 200 has the following capabilities. Additionally, information regarding whether the terminal 200 has the following capabilities may be reported to the network (for example, the communication nodes 100a, 100b).

- Ability to report retention information - Ability to set specific triggers The ability to report retention information may include the message type used for reporting. Examples of message types include RRC messages, PDCP control PDUs such as PDCP status reports, MAC CE, and L1 signals.

The ability to report retention information may include reportable information types, reportable granularity, methods of reporting retention information, and the like. Reportable granularity includes reporting per layer, reporting per layer and between layers, data granularity and precision (for example, bytes, kilobytes, or megabytes), reporting per UL and DL, and reporting per QoS. Examples include whether or not it is possible.

The ability to set specific triggers may include the number of triggers that can be set, the types of triggers that can be set, and the like.

The block diagrams (FIGS. 4 and 5) used to explain the embodiments described above show blocks in functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of implementing each functional block is not particularly limited. That is, each functional block may be realized using one physically or logically coupled device, or may be realized using two or more physically or logically separated devices directly or indirectly (e.g. , wired, wireless, etc.) and may be realized using a plurality of these devices. The functional block may be realized by combining software with the one device or the plurality of devices.

Functions include judgment, decision, judgment, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, consideration, notification ( Examples include, but are not limited to, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assigning. . For example, a functional block (configuration unit) that performs transmission is called a transmitting unit or a transmitter. In either case, as described above, the implementation method is not particularly limited.

Furthermore, the communication nodes 100a, 100b and terminal 200 described above may function as a computer that performs processing of the wireless communication method of the present disclosure. FIG. 11 is a diagram showing an example of the hardware configuration of the communication node and the terminal. As shown in FIG. 11, the communication node and the terminal may be configured as a computer device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, and the like.

In addition, in the following description, the word "apparatus" can be read as a circuit, a device, a unit, etc. The hardware configuration of the device may include one or more of the devices shown in the figure, or may not include some of the devices.

Each functional block of the device is realized by any hardware element of the computer device or a combination of hardware elements.

In addition, each function in the device is performed by loading predetermined software (programs) onto hardware such as the processor 1001 and memory 1002, so that the processor 1001 performs calculations, controls communication by the communication device 1004, and controls the memory This is realized by controlling at least one of data reading and writing in the storage 1002 and the storage 1003.

The processor 1001, for example, operates an operating system to control the entire computer. The processor 1001 may be configured by a central processing unit (CPU) that includes interfaces with peripheral devices, a control device, an arithmetic device, registers, and the like.

Furthermore, the processor 1001 reads programs (program codes), software modules, data, and the like from at least one of the storage 1003 and the communication device 1004 to the memory 1002, and executes various processes in accordance with these. As the program, a program that causes a computer to execute at least part of the operations described in the above embodiments is used. Further, the various processes described above may be executed by one processor 1001, or may be executed by two or more processors 1001 simultaneously or sequentially. Processor 1001 may be implemented by one or more chips. Note that the program may be transmitted from a network via a telecommunications line.

The memory 1002 is a computer-readable recording medium, and includes at least one of Read Only Memory (ROM), Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), Random Access Memory (RAM), etc. may be done. Memory 1002 may be called a register, cache, main memory, or the like. The memory 1002 can store programs (program codes), software modules, etc. that can execute a method according to an embodiment of the present disclosure.

The storage 1003 is a computer-readable recording medium, such as an optical disk such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (such as a compact disk, a digital versatile disk, or a Blu-ray disk). (registered trademark disk), smart card, flash memory (eg, card, stick, key drive), floppy disk, magnetic strip, etc. Storage 1003 may also be called auxiliary storage. The above-mentioned recording medium may be, for example, a database including at least one of memory 1002 and storage 1003, a server, or other suitable medium.

The communication device 1004 is hardware (transmission/reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, a communication module, or the like.

The communication device 1004 includes, for example, a high frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). It may be composed of.

The input device 1005 is an input device (eg, keyboard, mouse, microphone, switch, button, sensor, etc.) that accepts 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. Note that the input device 1005 and the output device 1006 may have an integrated configuration (for example, a touch panel).

Further, 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 using a single bus, or may be configured using different buses for each device.

Furthermore, the device may include hardware such as a microprocessor, digital signal processor (DSP), application specific integrated circuit (ASIC), programmable logic device (PLD), and field programmable gate array (FPGA). A part or all of each functional block may be realized by the hardware. For example, processor 1001 may be implemented using at least one of these hardwares.

Furthermore, the notification of information is not limited to the aspects/embodiments described in this disclosure, and may be performed using other methods. For example, notification of information may be performed using physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), upper layer signaling (e.g., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block), etc. (MIB), System Information Block (SIB)), other signals, or a combination thereof. RRC signaling may also be referred to as RRC messages, such as RRC Connection Setup (RRC Connection Setup). ) message, RRC Connection Reconfiguration message, etc.

Each aspect/embodiment described in this disclosure is applicable to Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system ( 5G), Future Radio Access (FRA), New Radio (NR), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)) , IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth (registered trademark), and other suitable systems and next-generation systems extended based thereon. may be applied to. Furthermore, a combination of multiple systems (for example, a combination of at least one of LTE and LTE-A with 5G) may be applied.

The order of the processing procedures, sequences, flowcharts, etc. of each aspect/embodiment described in this disclosure may be changed as long as there is no contradiction. For example, the methods described in this disclosure use an example order to present elements of the various steps and are not limited to the particular order presented.

The specific operations performed by the base station in this disclosure may be performed by its upper node in some cases. In a network consisting of one or more network nodes including a base station, various operations performed for communication with a terminal are performed by the base station and other network nodes other than the base station (e.g., MME or It is clear that this can be done by at least one of the following: (conceivable, but not limited to) S-GW, etc.). Although the case where there is one network node other than the base station is illustrated above, it may be a combination of multiple other network nodes (for example, MME and S-GW).

Information, signals (information, etc.) may be output from an upper layer (or lower layer) to a lower layer (or upper layer). It may be input/output via multiple network nodes.

The input/output information may be stored in a specific location (for example, memory) or may be managed using a management table. Information that is input and output may be overwritten, updated, or additionally written. The output information may be deleted. The input information may be sent to other devices.

Judgment may be made using a value expressed by 1 bit (0 or 1), a truth value (Boolean: true or false), or a comparison of numerical values (for example, a predetermined value). (comparison with a value).

Each aspect/embodiment described in this disclosure may be used alone, may be used in combination, or may be switched and used in accordance with execution. In addition, notification of prescribed information (for example, notification of "X") is not limited to being done explicitly, but may also be done implicitly (for example, not notifying the prescribed information). Good too.

Software includes instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, whether referred to as software, firmware, middleware, microcode, hardware description language, or by any other name. , should be broadly construed to mean an application, software application, software package, routine, subroutine, object, executable, thread of execution, procedure, function, etc.

Additionally, software, instructions, information, etc. may be sent and received via a transmission medium. For example, if the software uses wired technology (coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), etc.) and/or wireless technology (infrared, microwave, etc.) to When transmitted from a server or other remote source, these wired and/or wireless technologies are included within the definition of transmission medium.

The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may refer to voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, light fields or photons, or any of the foregoing. It may also be represented by a combination of

Note that terms explained in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and the symbol may be a signal. Also, the signal may be a message. Furthermore, a component carrier (CC) may also be called a carrier frequency, cell, frequency carrier, or the like.

As used in this disclosure, the terms "system" and "network" are used interchangeably.

In addition, the information, parameters, etc. described in this disclosure may be expressed using absolute values, relative values from a predetermined value, or using other corresponding information. may be expressed. For example, radio resources may be indicated by an index.

The names used for the parameters described above are not restrictive in any respect. Furthermore, the mathematical formulas etc. using these parameters may differ from those explicitly disclosed in this disclosure. Since the various channels (e.g. PUCCH, PDCCH, etc.) and information elements can be identified by any suitable designation, the various names assigned to these various channels and information elements are in no way exclusive designations. isn't it.

In this disclosure, "Base Station (BS)," "wireless base station," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," " "access point", "transmission point", "reception point", "transmission/reception point", "cell", "sector", "cell group", " The terms "carrier", "component carrier", etc. may be used interchangeably. A base station may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

A base station can accommodate one or more (eg, three) cells (also called sectors). If a base station accommodates multiple cells, the overall coverage area of the base station can be partitioned into multiple smaller areas, and each smaller area is divided into base station subsystems (e.g., small indoor base stations (Remote Radio Communication services can also be provided by Head: RRH).

The term "cell" or "sector" refers to part or all of the coverage area of base stations and/or base station subsystems that provide communication services in this coverage.

In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably. .

A mobile station is defined by a person 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 referred to as a terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

At least one of a base station and a mobile station may be called a transmitting device, a receiving device, a communication device, or the like. Note that at least one of the base station and the mobile station may be a device mounted on a mobile body, the mobile body itself, or the like. The moving object may be a vehicle (for example, a car, an airplane, etc.), an unmanned moving object (for example, a drone, a self-driving car, etc.), or a robot (manned or unmanned). ). Note that at least one of the base station and the mobile station includes devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an Internet of Things (IoT) device such as a sensor.

Furthermore, the base station in the present disclosure may be read as a mobile station (user terminal, hereinafter the same). For example, communication between a base station and a mobile station is replaced with communication between multiple mobile stations (for example, it may be called Device-to-Device (D2D), Vehicle-to-Everything (V2X), etc.). Regarding the configuration, each aspect/embodiment of the present disclosure may be applied. In this case, the mobile station may have the functions that the base station has. Further, words such as "up" and "down" may be replaced with words corresponding to inter-terminal communication (for example, "side"). For example, uplink channels, downlink channels, etc. may be replaced with side channels.

Similarly, the mobile station in the present disclosure may be read as a base station. In this case, the base station may have the functions that the mobile station has.

The terms "connected", "coupled", or any variations thereof, refer to any connection or coupling, direct or indirect, between two or more elements and to each other. It may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled." The bonds or connections between elements may be physical, logical, or a combination thereof. For example, "connection" may be replaced with "access." As used in this disclosure, two elements may include one or more wires, cables, and/or printed electrical connections, as well as in the radio frequency domain, as some non-limiting and non-inclusive examples. , electromagnetic energy having wavelengths in the microwave and optical (both visible and non-visible) ranges, and the like.

The reference signal may also be abbreviated as Reference Signal (RS), and may be called a pilot depending on the applicable standard.

As used in this disclosure, the phrase "based on" does not mean "based solely on" unless explicitly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

As used in this disclosure, any reference to elements using the designations "first," "second," etc. does not generally limit the amount or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Thus, reference to a first and second element does not imply that only two elements may be employed therein or that the first element must precede the second element in any way.

Where "include", "including" and variations thereof are used in this disclosure, these terms, like the term "comprising," are inclusive. It is intended that Furthermore, the term "or" as used in this disclosure is not intended to be exclusive or.

In this disclosure, when articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are plural.

In this disclosure, the term "A and B are different" may mean "A and B are different from each other." Note that the term may also mean that "A and B are each different from C". Terms such as "separate" and "coupled" may also be interpreted similarly to "different."

Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure can be implemented as modifications and variations without departing from the spirit and scope of the present disclosure as determined by the claims. Therefore, the description of the present disclosure is for the purpose of illustrative explanation and is not intended to have any limiting meaning on the present disclosure.

The above-described terminal is useful because it can reliably prevent overflow from occurring in the layer 2 level buffer of the terminal when the terminal communicates using radio resources provided by multiple communication nodes. .

10 Wireless communication system
100a, 100b communication node
110 Transmitter
120 Receiver
130 Timer
140 Management Department
150 Control section
200 terminals
210 Transmitter
220 Receiver
230 timer
240 layer 2 buffer
250 Control section
1001 processor
1002 memory
1003 Storage
1004 Communication equipment
1005 Input device
1006 Output device
1007 bus

Claims (4)

A terminal,
Information indicating the retention state of all data retained in a buffer that stores uplink data and downlink data communicated using multiple radio bearers set between the terminal and multiple communication nodes, is transmitted to the multiple communication nodes. a transmitter that transmits to each of the communication nodes;
a control unit that causes the transmission unit to transmit information indicating the retention state based on a specific trigger;
Equipped with
In the terminal, the amount of downlink data that can be stored in the buffer varies depending on the total amount of uplink data and downlink data that is stored in the buffer. The terminal according to claim 1, wherein the control section causes the transmission section to transmit information indicating the retention state at regular intervals. A communication node,
First information indicating the retention state of data retained in a buffer of the terminal that stores uplink data and downlink data communicated using a radio bearer configured between the terminal and the communication node, a transmitter that transmits to a communication node;
Second information indicating a retention state of data retained in a buffer of the terminal that stores uplink data and downlink data communicated using a radio bearer set between the terminal and another communication node, a receiving unit that receives from the other communication node;
a control unit that controls transmission of new downlink data based on the first information and the second information ;
Equipped with
A communication node in which the amount of downlink data that can be stored in the buffer of the terminal varies depending on the total amount of uplink data and downlink data that is stored in the buffer of the terminal. The communication node according to claim 3, wherein the control unit causes the transmitter to transmit the first information at regular intervals.

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