KR102197852B1 - Method and apparatus for controlling buffer - Google Patents

Abstract

A method of managing a buffer of the secondary base station in a dual connection mode between a master base station and a secondary base station of a communication system, the method comprising: receiving a secondary base station addition request (SeNB ADDITION REQUEST) message requesting the establishment of a new bearer from the master base station, There is provided a buffer management method comprising determining whether the buffer is in an overload state, and if the buffer is not in an overload state, determining whether to accept a request for setting up the new bearer according to a bearer type of the new bearer. .

Description

Buffer management method and apparatus {METHOD AND APPARATUS FOR CONTROLLING BUFFER}

The present disclosure relates to a method and apparatus for managing a buffer of a secondary base station in a dual connection mode between a master base station and a secondary base station of a communication system.

Technologies for increasing traffic transmission capacity using a plurality of cells in LTE mobile communication include a carrier aggregation technology and a dual connectivity technology. These technologies are classified according to the network structure, the branching protocol layer and the role of the radio control channel.

The dual connectivity technology is a technology that increases the transmission rate by using radio resources of two or more base stations in a non-ideal backhaul network structure that does not guarantee accurate synchronization between base stations. Dual connectivity technology is the UP (User Plane) 3C method and EPC (Evolved) that distributes and transmits traffic from the PDCP (Packet Data Convergence Protocol) layer of L2 to the Radio Link Control (RLC) layer of two base stations according to the structure of the user plane. Packet Core) is divided into UP 1A, which separates and transmits traffic for each bearer.

The UP 3C scheme is a scheme in which traffic of one bearer is distributed and transmitted by a master base station and a secondary base station. In the UP 3C scheme, the master base station transmits a portion of a packet received from the EPC to the secondary base station, and the secondary base station transmits the received packet to the terminal.

In the UP 3C scheme, since a non-ideal backhaul connection between a master base station and a secondary base station is provided, a packet transmission delay may occur.

In the UP 3C method, transmission delay or buffer overload may occur when more packets are received by the master base station compared to the packet transmission rate of the secondary base station. Conversely, radio resources are efficient when fewer packets are received by the master base station compared to the packet rate of the secondary base station. There is a problem that it cannot be used.

An embodiment provides a method and apparatus for managing a buffer of a secondary base station in a dual connection mode between a master base station and a secondary base station of a communication system.

According to an embodiment, a method of managing a buffer of the secondary base station in a dual connection mode between a master base station and a secondary base station of a communication system is provided. The buffer management method includes receiving a secondary base station addition request (SeNB ADDITION REQUEST) message requesting the establishment of a new bearer from the master base station, determining whether the buffer is in an overload state, and the buffer is in an overload state. Otherwise, determining whether to accept the request for setting up the new bearer according to the bearer type of the new bearer.

In determining whether the buffer is in an overload state, it may be determined whether the buffer is in an overload state based on an amount of radio resources of a terminal for each bearer type of the new bearer.

The step of determining whether to accept the request for setting up the new bearer may include, if the bearer type of the new bearer is a guaranteed bit rate (GBR), the setting of the new bearer based on whether or not there are remaining allocable resources for GBR. You can decide whether to accept the request or not.

The step of determining whether to accept the request for setting up the new bearer may include determining whether to accept the request for setting up the new bearer if the bearer type of the new bearer is non-Guaranteed Bit Rate (non-GBR). have.

According to another embodiment, an apparatus for managing a buffer of the secondary base station in a dual connection mode between a master base station and a secondary base station of a communication system is provided. The buffer management apparatus determines whether a bearer receiver receiving a SeNB ADDITION REQUEST message requesting the establishment of a new bearer from the master base station, and whether the buffer is in an overload state, and the buffer is in an overload state. Otherwise, it includes a radio resource management unit that determines whether to accept the request for setting up the new bearer according to the bearer type of the new bearer.

The radio resource management unit may determine whether the buffer is in an overloaded state based on an amount of radio resources of a terminal for each bearer type of the new bearer.

If the bearer type of the new bearer is a guaranteed bit rate (GBR), the radio resource management unit may determine whether to accept the request for setting the new bearer based on whether there is a remaining resource that can be allocated for GBR.

When the bearer type of the new bearer is non-Guaranteed Bit Rate (non-GBR), the radio resource management unit may determine whether to accept the request for setting up the new bearer.

In the dual connectivity mode, it is possible to increase the efficiency of radio resources of the secondary base station through traffic management transmitted between the master base station and the secondary base station, and to increase the transmission rate of a region.

In addition, if the secondary base station is not in an overload state, the load on the master base station can be reduced by distributing traffic to the secondary base station.

In addition, when the secondary base station is overloaded, the traffic flow can be adjusted by interworking with the master base station.

1 is a diagram illustrating a network structure of a UP 3C scheme having dual connectivity according to an embodiment.
2 is a diagram illustrating a protocol structure between a master base station and a secondary base station according to an embodiment.
3 is a block diagram of a buffer management apparatus of a secondary base station according to an embodiment.
4 is a flowchart of a buffer management method of a secondary base station according to an embodiment.
5 is a flowchart of a buffer management method of a secondary base station according to another embodiment.
6 is a block diagram of a wireless communication system according to an embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the embodiments of the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and similar reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

Throughout the specification, a terminal is a user equipment (UE), a mobile station (MS), a mobile terminal (MT), an advanced mobile station (AMS), and a highly reliable mobile station. (high reliability mobile station, HR-MS), subscriber station (SS), portable subscriber station (PSS), access terminal (AT), machine type communication device, MTC device) and the like, and may include all or part of functions such as UE, MS, MT, AMS, HR-MS, SS, PSS, AT, and the like.

In addition, the base station (BS) is a node B (node B), an advanced node B (evolved node B, eNB), gNB, an advanced base station (ABS), a high reliability base station, HR-BS), access point (AP), radio access station (RAS), base transceiver station (BTS), mobile multihop relay (MMR)-BS, repeater serving as a base station (relay station, RS), a relay node (RN) that acts as a base station, an advanced relay station (ARS) that acts as a base station, and a high reliability relay station that acts as a base station. , HR-RS), small base stations (femto BS), home node B (home node B, HNB), home eNodeB (HeNB), pico base station (pico BS), macro base station (macro BS), micro base station ( micro BS), etc.], and all or part of functions such as NB, eNB, gNB, ABS, AP, RAS, BTS, MMR-BS, RS, RN, ARS, HR-RS, small base stations, etc. It can also be included.

1 is a diagram illustrating a network structure of an UP 3C scheme having dual connectivity in an LTE mobile communication network according to an embodiment.

Referring to Figure 1, the UP 3C network is a terminal 10, a master base station 100 and a secondary base station 200 that transmits data to the terminal 10, the mobility of the authentication and mobility management of the terminal 10. A mobility management entity (MME) 300 and a gateway (GW) 400 that distributes traffic to the master base station 100 and the secondary base station 200 are included.

In the UP 3C method with dual connectivity, a base station having a radio resource control (RRC) connection with the terminal 10 is referred to as a master base station, and user traffic is transmitted to the terminal 10 under the control of the master base station. The base station is called a secondary base station. The master base station 100 controls the terminal 10 and transmits user traffic to the terminal 10.

The connection between the master base station 100 and the secondary base station 200 is a non-ideal backhaul connection that does not guarantee real-time transmission.

The terminal 10 may be a plurality of terminals as an embodiment.

2 is a diagram showing the structure of a protocol between a master base station and a secondary base station according to an embodiment.

2, the traffic transmitted from the Evolved Packet Core (EPC) 30 is transmitted to the Packet Data Convegence Protocol (PDCP) 120 through the GPRS Tunneling Protocol (GTP) 110 of the master base station 100. . The PDCP 120 of the master base station 100 transmits some traffic of a bearer to the Radio Link Control (RLC) 140 of the secondary base station 200.

The secondary base station 200 transmits packets by allocating radio resources to the terminal 10 independently of the master base station 100 according to the radio state. At this time, there may be a discrepancy between the amount of packets transmitted from the secondary base station 200 to the terminal 10 and the amount of packets transmitted from the master base station 100 to the secondary base station 200. According to the present description, the secondary base station 200 Inconsistency between packet amounts can be solved through buffer management of

3 is a block diagram of a buffer management apparatus of a secondary base station according to an embodiment.

Referring to FIG. 3, the buffer management apparatus 210 of the auxiliary base station 200 according to an embodiment includes a scheduler 211, a radio resource management unit 212, and a bearer reception unit 213.

Since the amount of the allocated radio resource varies according to the state of the radio channel of each terminal of the terminal 10 including a plurality of terminals, it is calculated through an average value of statistical values measured at a certain period.

The scheduler 211 displays the physical resource block (PRB) usage and average channel quality for guaranteed bit rate (GBR) and non-Guaranteed Bit Rate (non-GBR) of each terminal. (Channel Quality Indication, CQI) is measured at a predetermined period, and the measurement result is transmitted to the radio resource management unit 212. In one embodiment, the predetermined period may be 1 second.

The radio resource management unit 212 obtains the state of the radio resource using the PRB usage of each terminal and the average CQI, and transmits a downlink data delivery status message to the master base station 100.

The state of the radio resource is calculated through Equations 1 to 3.

The bearer reception unit 213 receives the bearer from the master base station 100, calculates a packet transmission rate for each received bearer, and transmits the calculated packet transmission rate to the radio resource management unit 212 for each measurement period.

4 is a flowchart of a buffer management method of a secondary base station according to an embodiment.

Referring to FIG. 4, a method of managing a buffer of a secondary base station according to an embodiment includes the step of receiving a secondary base station addition request (SeNB ADDITION REQUEST) message requesting the establishment of a new bearer from a master base station (S100), Determining whether the buffer is in an overload state (S200), and if the buffer of the secondary base station is not in an overload state, determining whether to accept a request for setting up a new bearer according to the bearer type of the new bearer (S300).

In step S100 of receiving a secondary base station addition request (SeNB ADDITION REQUEST) message, the bearer receiver 213 receives a secondary base station addition request (SeNB ADDITION REQUEST) message (first message) from the master base station 100.

In the step of determining whether the buffer of the secondary base station is overloaded (S200), the radio resource management unit 212 determines whether the buffer is overloaded based on the radio resource usage of the terminal for each bearer type received from the scheduler 211. do.

Whether the buffer of the secondary base station 200 is overloaded is determined through Equation 4. When the value of Equation 4 is greater than α, the buffer of the secondary base station 200 indicates an overload state. The closer the value of Equation 4 is to 1, the greater the degree of overload.

α represents a reference value for a preset overload condition.

If the value of Equation 4 is less than α, the radio resource management unit 212 rejects the request for setting up a new bearer (S210).

If the buffer of the secondary base station 200 is not in an overload state, in the step (S300) of determining whether to accept a request for setting up a new bearer according to the bearer type of the new bearer, the radio resource management unit 212 determines that the bearer type of the new bearer is In the case of guaranteed (Guaranteed Bit Rate, GBR), it is determined whether to accept the request for setting up a new bearer based on whether there are remaining resources available for GBR (S311, S312, S313). It is determined based on Equation (5) whether or not there are remaining allocable resources for GBR. If the value of Equation 5 is less than β, the request for setting up a new bearer is accepted (S312). Otherwise, the request for setting a new bearer is rejected (S313).

The first GBR refers to a GBR in consideration of a measurement period of a SeNB ADDITION REQUEST message of a newly added terminal. β represents a reference value for whether there are remaining allocable resources for GBR set in advance. The value of Equation 5 denotes an allocation ratio of GBR resources to all resources allocated for GBR bearers. If the value of Equation 5 is greater than β, it means that the resource allocation ratio for GBR is high.

If the bearer type of the new bearer is non-Guaranteed Bit Rate (non-GBR), the radio resource management unit 212 accepts a request for setting up a new bearer (S314). Excessive acceptance of a request for setting a new bearer for non-GBR may cause an overload of the buffer of the secondary base station 200.

When it is determined whether to accept the request for setting up a new bearer (S312, S313, S314), the radio resource management unit 212 includes the acceptance result in a secondary eNB addition request response (Secondary eNB: SeNB ADDITION REQUEST ACKNOWLEDGE) message (second message) Then, it is transmitted to the master base station 100 (S400).

5 is a flowchart of a buffer management method of a secondary base station according to another embodiment.

Referring to FIG. 5, a method of managing a buffer of a secondary base station according to another embodiment includes the step of periodically measuring a radio resource usage of a terminal (S500), and a bearer type received from a master base station, a packet transmission rate, and an overload state of a buffer. And controlling the requested buffer size of the secondary base station based on whether or not (S600).

In the step of measuring the radio resource usage of the terminal (S500), the scheduler 211 periodically measures the radio resource usage of the terminal for each bearer type through a timer.

In the step of controlling the request buffer size (S600), the radio resource management unit 212 determines the type of the bearer received from the master base station 100 by the bearer receiving unit 213 (S610). If the bearer type is GBR, the buffer is not overloaded, and the packet transmission rate is equal to a preset reference value (S611), the radio resource management unit 212 determines the requested buffer size of the downlink data delivery status message in Equation 6 It increases based on (S612).

The initial guaranteed bit rate (Guaranteed Bit rate) is a guaranteed bit rate set by the master base station 100 (Guaranteed Bit rate).

The radio resource management unit 212 reflects the increased guaranteed bit rate to the requested buffer size in the downlink data delivery status message and transmits it to the master base station 100 (S613).

When the bearer type is non-GBR, the buffer is not in an overloaded state, and the packet transmission rate is equal to a preset reference value (S614), the radio resource management unit 212 calculates the request buffer size of the downlink data delivery status message. It increases based on 7 (S615).

The initial request buffer size is set to 0.

If the bearer type is non-GBR and the buffer is overloaded (S616), the radio resource management unit 212 reduces the requested buffer size of the bearer that has transmitted more packets than the requested buffer size among bearers based on Equation 8. (S617).

6 is a block diagram of a wireless communication system according to an embodiment.

Referring to FIG. 6, a wireless communication system according to an embodiment includes a base station 1510 and a terminal 1520.

The base station 1510 includes a processor (processor) 1511, a memory (memory) 1512, and a radio communication unit (radio frequency unit, RF unit) 1513.

The memory 1512 may be connected to the processor 1511 to store various pieces of information for driving the processor 1511 or at least one program executed by the processor 1511. The wireless communication unit 1513 is connected to the processor 1511 to transmit a wireless signal to the packet input through the network switch to the processor 1511, and output and transmit/receive the packet processed by the processor 1511 to the outside of the network switch. . The processor 1511 may implement a function, process, or method proposed in the embodiments of the present disclosure. In this case, in the wireless communication system according to the exemplary embodiment of the present disclosure, the radio interface protocol layer may be implemented by the processor 1511. The operation of the base station 1510 according to an embodiment may be implemented by the processor 1511.

The terminal 1520 includes a processor 1521, a memory 1522, and a wireless communication unit 1523. The memory 1522 may be connected to the processor 1521 to store various pieces of information for driving the processor 1521 or at least one program executed by the processor 1521. The wireless communication unit 1523 is connected to the processor 1521 to transmit and receive wireless signals. The processor 1521 may implement the functions, steps, or methods proposed in the embodiments of the present disclosure. In this case, in the wireless communication system according to the exemplary embodiment of the present disclosure, the radio interface protocol layer may be implemented by the processor 1521. The operation of the terminal 1520 according to an embodiment may be implemented by the processor 1521.

In the embodiment of the present disclosure, the memory may be located inside or outside the processor, and the memory may be connected to the processor through various known means. The memory is various types of volatile or nonvolatile storage media. For example, the memory may include a read-only memory (ROM) or a random access memory (RAM).

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (8)

A method for the secondary base station to manage a buffer in a dual connection mode of a master base station and a secondary base station of a communication system,
Adjusting the requested buffer size of the bearer based on the type of bearer received from the master base station, the packet transmission rate for each bearer, and whether the buffer is overloaded,
Transmitting a downlink transmission status message reflecting the adjusted request buffer size of the corresponding bearer to the master base station,
Receiving a request for setting up a new bearer from the master base station,
Determining whether the buffer is in an overload state, and
If the buffer is not in an overload state, determining whether to accept the request for setting up the new bearer according to the bearer type of the new bearer
Buffer management method comprising a. In claim 1,
The adjusting step
If the bearer type is a guaranteed bit rate (GBR), the buffer is not overloaded, and the packet transmission rate is equal to a preset reference value, increasing the requested buffer size of the bearer,
If the bearer type is non-Guaranteed Bit Rate (non-GBR), the buffer is not overloaded, and the packet transmission rate is equal to a preset reference value, increasing the size of the requested buffer of the bearer, and
And if the bearer type is non-GBR and the buffer is overloaded, reducing the requested buffer size of a bearer that has transmitted more packets than the requested buffer size among bearers. In claim 1,
The step of determining whether to accept the request for setting up the new bearer is a request for setting up the new bearer based on whether or not there are remaining allocable resources for GBR if the bearer type of the new bearer is a guaranteed bit rate (GBR). Buffer management method comprising the step of determining whether to accept or not. In claim 1,
The step of determining whether to accept the request for setting up the new bearer may include determining whether to accept the request for setting up the new bearer if the bearer type of the new bearer is non-Guaranteed Bit Rate (non-GBR). Buffer management method comprising a. An apparatus for managing a buffer of the secondary base station in a dual connection mode between a master base station and a secondary base station of a communication system,
A bearer receiver for receiving a request for setting up a new bearer from the master base station, and
Determine whether the buffer is in an overload state, and if the buffer is not in an overload state, determine whether to accept the request for setting up the new bearer according to the bearer type of the new bearer, and the type of bearer received from the master base station and A radio resource management unit that adjusts the requested buffer size of the bearer based on the respective packet transmission rate and whether the buffer is overloaded, and transmits a downlink transmission status message reflecting the adjusted request buffer size of the corresponding bearer to the master base station.
Buffer management device comprising a. In clause 5,
When the type of the bearer is a guaranteed bit rate (GBR), the buffer is not overloaded, and the packet transmission rate is equal to a preset reference value, the radio resource management unit increases the requested buffer size of the bearer. In clause 5,
When the bearer type of the new bearer is a guaranteed bit rate (GBR), the radio resource management unit accepts the request for setting up the new bearer when there is a remaining resource available for GBR, and the bearer type of the new bearer is If the bit rate is non-guaranteed (non-Guaranteed Bit Rate, non-GBR), a buffer management device that accepts the request for setting up the new bearer. In clause 5,
When the type of the bearer is non-Guaranteed Bit Rate (non-GBR), the buffer is not overloaded, and the packet transmission rate is equal to a preset reference value, the radio resource management unit increases the requested buffer size of the bearer. And if the bearer type is non-GBR and the buffer is overloaded, the buffer management apparatus reduces the requested buffer size of a bearer that has transmitted more packets than the requested buffer size among bearers.

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