JP2014017591A - Base station and wireless communication system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide techniques to properly control the connection state of a UE in a buffer status reporting mechanism.SOLUTION: A base station 100 includes: a UE data retaining amount management unit 140 that manages the amount of downlink data and/or uplink data transmitted/received to/from a user device; a Release Pending Timer management unit 150 that starts a second timer when a message indicating that uplink data has been generated is received from the user device, and stops and resets the second timer when uplink traffic data is received from the user device; and a UE state management unit 130 that causes the user device to transition from a connection-established state to an idle state when a first timer managed by a UE Inactive Timer management unit 160 exceeds a prescribed threshold while the second timer managed by the Release Pending Timer management unit 150 is not running.

Description

  The present invention generally relates to a radio communication system, and more particularly to a technique for controlling a connection state of a user apparatus by a base station of the radio communication system.

  LTE (Long Term Evolution) has been developed as a communication standard for high-speed communication of large volumes of data, and its specifications have been formulated by the standardization organization 3GPP (Third Generation Partnership Project).

  In the LTE system, when uplink (UL) data is generated in a user equipment (User Equipment: UE), a buffer status report (Buffer Status Report: BSR) mechanism that reports the generated data amount to a base station (eNodeB: eNB). Is stipulated. In this BSR mechanism, the UE reports the UL data amount staying in the UE for each logical channel group (Logical Channel Group: LCG) to the base station. In addition, a plurality of logical channels (Logical Channel: LCH) can be mapped to one LCG. In this case, the UE reports the total amount of data of the plurality of mapped LCHs to the eNB as the buffer amount of the LCG. To do.

  For example, in the BSR as shown in FIG. 1, LCH # 1 and LCH # 2 are mapped to LCG # 1. In this case, the UE reports the total data amount of 150 bytes including the LCH # 1 data amount of 50 bytes and the LCH # 2 data amount of 100 bytes to the eNB as the LCG # 1 UL data amount.

  In the LTE system, the UE has two states, an RRC connected state and an idle state. In the RRC connected state, a connection is established between the UE and the eNB, and the UE can transmit and receive data to and from the eNB. On the other hand, in the idle state, if the connection is not established between the UE and the eNB and the UE tries to transmit / receive data to / from the eNB, the UE transitions to the RRC connected state and establishes the connection. There is a need. For a UE having data, it is desirable that the UE is in an RRC connected state so that data can be transmitted and received quickly. On the other hand, for UEs that do not have data, the UE is preferably in an idle state from the viewpoint of saving network resources and UE battery.

  For this reason, in the LTE system, generally, when there is no data to be transmitted / received for a predetermined time in the UE, the UE is shifted to an idle state. Specifically, the eNB monitors the presence / absence of downlink / uplink (DL / UL) U-plane data for the UE, and activates the UE Inactive Timer when there is no DL / UL U-plane data for the UE. To do. Thereafter, when the DL / UL U-plane data for the UE is generated, the eNB resets the UE Inactive Timer and stops. On the other hand, when the DL / UL U-plane data for the UE is not generated and the UE Inactive Timer exceeds a predetermined time threshold, the eNB transitions the UE to an idle state.

  Here, as a method for the eNB to determine that DL / UL U-plane data for the UE has occurred, there is the following method. That is, for DL data, when DL U-plane data arrives at the eNB from an upper station or the like, the eNB determines that DL U-plane data has been generated. On the other hand, for UL data, in response to receiving a BSR from the UE, or in response to receiving a UL MAC (Medium Access Control) PDU (Protocol Data Unit) from the UE, the eNB It is determined that U-plane data has been generated.

3GPP TS 36.321 V8.12.0 (2012-03)

  However, when the above-described determination of generation of UL data is based on the BSR reported from the UE, the eNB may not be able to determine whether the data reported by the BSR is C-plane data or U-plane data. For example, in the specific example of the BSR shown in FIG. 1, both DCG (Dedicated Control Channel) that is a C-plane logical channel and DTCH (Dedicated Traffic Channel) that is a U-plane logical channel are included in LCG # 1. In the case of mapping, the UE reports the total data amount of DCCH and DTCH as the retained data amount of LCG # 1 without distinguishing between DCCH and DTCH. For this reason, the eNB that has received the BSR cannot determine whether C-plane data or U-plane data has occurred in the UE.

  With reference to FIG. 2, a conventional control method using UE Inactive Timer in the case of determining the generation of UL data by receiving the BSR described above will be described in more detail. FIG. 2 is a diagram illustrating an outline of operation of a conventional UE Inactive Timer. As shown in FIG. 2, when UL data is generated in the UE, the UE reports the UL data amount staying for each LCG to the eNB by BSR. As described above, in response to the reception of the BSR from the UE, the eNB determines that UL U-plane data has been generated for the UE, and stops and resets the UE Inactive Timer. Thereafter, UL data (such as the illustrated MAC PDU) is transmitted from the UE, and when the U-plane data for the UE disappears and the transmission of the UL data from the UE ends, the eNB receives the UL U-plane data for the UE. It is determined that it has run out, and the UE Inactive Timer is restarted. Thereafter, when the UE Inactive Timer exceeds a predetermined time threshold, the eNB transmits an RRC connection release to the UE to disconnect the UE, and transitions the UE to an idle (IDLE) state.

  However, in the BSR described above, the data amount is reported as the total data amount of U-plane data and C-plane data without distinguishing between U-plane data and C-plane data. For this reason, in response to the reception of the BSR from the UE, when the eNB determines that U-plane data for the UE has occurred and stops and resets the UE Inactive Timer, only C-plane data is actually generated. In spite of this, the UE Inactive Timer is stopped and reset, and the UE Inactive Timer is stopped and reset at a timing that should not be stopped and reset. As a result, the opportunity to place the UE in an idle state is missed, and unnecessary network resources and the battery of the UE are consumed.

  In view of the above problems, an object of the present invention is to provide a technique for appropriately controlling the connection state of a UE in a buffer status report mechanism.

  One aspect of the present invention is a base station that communicates with a user apparatus in a wireless communication system, and a data retention amount management unit that manages the amount of downlink and / or uplink data transmitted to and received from the user apparatus; A first timer management unit for managing a first timer for measuring a period during which downlink and uplink traffic data transmitted / received to / from the user apparatus is not generated, and a first timer for suspending the stop and reset of the first timer A second timer management unit that manages two timers; and a user device state management unit that transitions the user device from a connection establishment state to an idle state when the first timer exceeds a predetermined threshold, When receiving a message notifying that uplink data has been generated from the user apparatus, the timer management unit receives the second type. And when the uplink traffic data is received from the user equipment, the second timer is stopped and reset, and the first timer management unit continues to start the first timer while the second timer is activated. Related to the base station.

  Another aspect of the present invention is a wireless communication system including a user apparatus and a base station that communicates with the user apparatus, wherein the base station transmits and receives downlink and / or uplink data to and from the user apparatus. A data retention amount management unit that manages a data amount of the first data, a first timer management unit that manages a first timer for measuring a period during which downlink and uplink traffic data transmitted to and received from the user apparatus is not generated, A second timer management unit that manages a second timer that holds suspension and resetting of the first timer; and, when the first timer exceeds a predetermined threshold, causes the user apparatus to transition from a connection established state to an idle state The second timer management unit notifies that uplink data has been generated from the user device. When the message is received, the second timer is started. When uplink traffic data is received from the user equipment, the second timer is stopped and reset, and the first timer management unit is starting the second timer. Relates to a wireless communication system in which the start of the first timer is continued.

  According to still another aspect of the present invention, there is provided a method for controlling a connection state of a user apparatus by a base station of a wireless communication system, wherein a period during which downlink and uplink traffic data transmitted to and received from the user apparatus is not generated. Determining whether a second timer for suspending the stop and reset of the first timer for timing is being activated, and receiving uplink traffic data from the user equipment when the second timer is activated Stopping and resetting the second timer, stopping and resetting the first timer, and if the second timer is not running, and if the first timer exceeds a predetermined threshold, And transitioning from a connection established state to an idle state.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which controls appropriately the connection state of UE in a buffer status report mechanism can be provided.

FIG. 1 is a diagram illustrating an example of a buffer status report. FIG. 2 is a diagram illustrating an outline of operation of a conventional UE Inactive Timer. FIG. 3 is a diagram illustrating an outline of the operation of the UE Iactive Timer according to an embodiment of the present invention. FIG. 4 is a diagram schematically illustrating a wireless communication system according to an embodiment of the present invention. FIG. 5 is a diagram illustrating a configuration of a base station according to an embodiment of the present invention. FIG. 6 is a flowchart illustrating idle state transition processing of the base station according to an embodiment of the present invention.

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

  In the embodiments disclosed below, the base station manages the amount of downlink and / or uplink data transmitted / received to / from the user equipment and generates downlink / uplink traffic data transmitted / received to / from the user equipment. It manages UE Inactive Timer for timing the period when it is not. When the UE Inactive Timer exceeds a predetermined threshold, the base station transitions the user apparatus from the connection establishment state to the idle state. In the conventional LTE system, when the base station receives the BSR from the user apparatus, the stay data reported by the BSR is either traffic data such as U-plane data or control data such as C-plane data. Regardless of whether there was a UE Inactive Timer stopped and reset.

  In the following embodiments, a Release Pending Timer that holds suspension and reset of UE Inactive Timer is provided in the base station. When the base station receives a BSR notifying that uplink data has been generated from the user apparatus, the base station activates a Release Pending Timer. Thereafter, when receiving traffic data such as uplink U-plane data from the user apparatus, the base station stops and resets the Release Pending Timer, and stops and resets the UE Inactive Timer. On the other hand, when only control data such as C-plane data is received from the user apparatus, the base station does not stop and reset the Release Pending Timer, and continues starting UE Inactive Timer while Release Pending Timer is starting. .

  Thus, only when traffic data is received instead of control data, the base station can stop and reset the UE Inactive Timer, and stop and reset the UE Inactive Timer at a timing that should not be stopped and reset. It becomes possible to avoid doing.

  FIG. 3 is a diagram illustrating an outline of the operation of the UE Inactive Timer according to an embodiment of the present invention. As illustrated in FIG. 3, when the base station (eNB) receives the BSR, the base station (eNB) suspends the transition of the user apparatus (UE) that has reported the BSR to the idle state without stopping the UE Inactive Timer. , Release Pending Timer is started. While starting the Release Pending Timer, the eNB continues to start the UE Inactive Timer. Upon detecting occurrence of DL / UL U-plane data, the eNB stops and resets the Release Pending Timer, and stops and resets the UE Inactive Timer. As a result, the eNB can stop and reset the UE Inactive Timer when U-plane data is generated, and can stop and reset the UE Inactive Timer when the BSR is transmitted due to the generation of C-plane data. It can be avoided.

  In the following description, an embodiment of an LTE-based wireless communication system is described, but the present invention is not limited to this, and may be applied to any other appropriate wireless communication system. In the following description, each embodiment will be described using a UE Inactive Timer of the LTE system, but the present invention is not limited to this. In other words, the present invention may be applied to any other appropriate timer for timing a period during which downlink and uplink traffic data transmitted / received to / from the user equipment is not generated. In the following description, each embodiment will be described using a buffer status report (BSR) of the LTE system, but the present invention is not limited to this. That is, the present invention may be applied to any other appropriate message that reports the amount of uplink data that remains in the user equipment. In the following description, each embodiment will be described using U-plane data and C-plane data of the LTE system, but the present invention is not limited to this. That is, the present invention may be applied to any other appropriate control information for controlling wireless communication with the user apparatus and traffic information such as actual data other than the control information.

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

  As illustrated in FIG. 4, the radio communication system 10 is an LTE system, and includes a base station (eNB) 100 and one or more user apparatuses (UE) 200. The UE 200 may typically be any appropriate user device having a wireless communication function such as a mobile phone or a smartphone as illustrated.

  The eNB 100 wirelessly connects to the UE 200 to transmit downlink (DL) data received from the upper station (not shown) to the UE 200 and to transmit uplink (UL) data received from the UE 200 to the upper station (not shown). Send).

  The UE 200 transmits and receives control data such as C-plane data and traffic data such as U-plane data to and from the eNB 200 by wirelessly connecting to the eNB 100.

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

  As illustrated in FIG. 5, the eNB 100 includes a downlink (DL) signal transmission unit 110, an uplink (UL) signal reception unit 120, a UE state management unit 130, a UE data retention amount management unit 140, and a Release. A Pending Timer management unit 150 and a UE Inactive Timer management unit 160 are included.

  DL signal transmission part 110 transmits DL signal to UE200. DL signals include traffic signals such as DL U-plane data transmitted to the UE 200, control signals such as C-plane data for wireless communication with the UE 200, and the like. For example, the DL signal transmission unit 110 transmits U-plane data received from an upper station (not shown) or the like to the destination UE 200 and also transmits C-plane data for controlling radio communication with the UE 200 to the UE 200. Send to.

  The UL signal receiving unit 120 receives a UL signal from the UE 200. Examples of the UL signal include a data signal such as UL U-plane data transmitted from the UE 200, a control signal such as C-plane data for wireless communication with the UE 200, and the like. In addition, when UL data is generated in the UE 200, the UL signal receiving unit 120 receives a buffer status report that reports the amount of data generated. The UL signal receiving unit 120 transmits the received various data to corresponding components of the eNB 100.

  The UE state management unit 130 manages the connection state of each UE 200, and transitions the UE 200 from the connection establishment state to the idle state when the UE Inactive Timer exceeds a predetermined threshold. In the LTE system, an RRC connected state and an idle (IDLE) state are defined as the connection state of the UE 200. In the RRC connected state, the radio connection between the eNB 100 and the UE 200 is established, and the UE 200 can transmit and receive data to and from the eNB 100. On the other hand, in the idle state, the radio connection between the eNB 100 and the UE 200 is not established, and the UE 200 cannot transmit / receive data to / from the eNB 100, and transits to the RRC connected state to transmit / receive data. There is a need. The UE 200 having data to be transmitted / received is preferably in an RRC connected state so that the data can be transmitted / received quickly, whereas the UE 200 not having data to be transmitted / received has a network resource or a battery of the UE 200. From the viewpoint of saving, it is desirable to be in an idle state. The UE state management unit 130 holds the UE Inactive Timer that measures the time when the UE 200 does not have traffic data to be transmitted / received such as U-plane data, which will be described in detail below, and the suspension and reset of the UE Inactive Timer. The connection state of the UE 200 is controlled based on the Release Pending Timer.

  The UE data retention amount management unit 140 manages the data amount of downlink and / or uplink data transmitted / received to / from each UE 200. Specifically, the UE data retention amount management unit 140 manages the data amount of DL U-plane data in the eNB 100 to be transmitted to the UE 200 for DL data, and the UL data in the UE 200 for UL data. Manage the amount of data. In the LTE system, when the UL data is generated, each UE 200 reports the UL data amount to the eNB 100 by using a BSR (Buffer Status Report) mechanism. That is, when the transmission target UL data is generated, the UE 200 reports the data amount of the UL data to the eNB 100. As described above, in this BSR mechanism, the UE 200 reports to the eNB 100 the UL data amount that stays for each logical channel group (LCG). In addition, a plurality of logical channels (Logical Channel: LCH) can be mapped to one LCG. In this case, the UE 200 reports the total data amount of the plurality of mapped LCHs to the eNB 100 as the buffer amount of the LCG. To do. The UE data retention amount management unit 140 manages the amount of data retained in the UE 200 based on the data amount of each LCG reported by the BSR transmitted from each UE 200.

  The Release Pending Timer management unit 150 manages a Release Pending Timer for suspending the UE 200 from transitioning to an idle state by suspending the stop and reset of the UE Inactive Timer. When receiving a message (such as BSR in the LTE system) notifying that uplink data has been generated from the UE 200, the Release Pending Timer management unit 150 activates the Release Pending Timer. Thereafter, when uplink traffic data is received from the UE 200, the Release Pending Timer management unit 150 stops and resets the Release Pending Timer. The UE Inactive Timer management unit 160 continues the activation of the UE Inactive Timer while the Release Pending Timer is activated.

  More specifically, when receiving the BSR from the UE 200, the Release Pending Timer management unit 150 activates the Release Pending Timer. Thereafter, when the eNB 100 detects U-plane data in a MAC (Medium Access Control) PDU (Protocol Data Unit) received from the UE 100, or when occurrence of DL U-plane data for the UE 200 is detected, Release The Pending Timer management unit 150 stops and resets the Release Pending Timer.

  When the reception of the staying data reported by the BSR is completed without receiving the U-plane data for the received BSR, the Release Pending Timer management unit 150 stops and resets the Release Pending Timer. Alternatively, the Release Pending Timer management unit 150 may determine that the Release Pending Timer has expired if the U-plane data has not been received until a predetermined period after the BSR is received, and stop and reset the Release Pending Timer. Good.

  The UE Inactive Timer management unit 160 manages a UE Inactive Timer for measuring a period in which no downlink and uplink traffic data transmitted / received to / from each UE 200 is generated. When there is no downlink or uplink traffic data transmitted to or received from the UE 200, the UE Inactive Timer management unit 160 activates the UE Inactive Timer and notifies the UE 200 that uplink data has been generated (such as a BSR in the LTE system). ), Since the Release Pending Timer is stopped and reset, the UE Inactive Timer is stopped and reset.

  In this embodiment, the UE Inactive Timer management unit 160 monitors whether or not DL / UL data for the UE 200 has been generated, and monitors whether the Release Pending Timer managed by the Release Pending Timer management unit 150 is being activated. As described above, when there is no DL / UL U-plane data for the UE 200, the UE Inactive Timer management unit 160 activates the UE Inactive Timer. Thereafter, when the UE data retention amount management unit 140 is notified that DL / UL U-plane data has been generated for the UE 200, the UE Inactive Timer management unit 160 activates the Release Pending Timer of the Release Pending Timer management unit 150. Check if it is inside. When the Release Pending Timer is being activated, the UE Inactive Timer management unit 160 continues the activation of the UE Inactive Timer. On the other hand, when the Release Pending Timer is not activated, the UE Inactive Timer management unit 160 stops and resets the UE Inactive Timer.

  In addition, after the UE Inactive Timer is activated, the UE Inactive Timer management unit 160 activates the Release Pending Timer when no DL / UL U-plane data is generated for the UE 200 and the UE Inactive Timer exceeds a predetermined time threshold. If not, the UE state management unit 130 is notified to shift the UE 200 to the idle state.

  FIG. 6 is a flowchart illustrating idle state transition processing of the base station according to an embodiment of the present invention.

  As illustrated in FIG. 6, in Step S101, the Release Pending Timer management unit 150 determines whether the Release Pending Timer is being activated, that is, whether the eNB 100 has received a BSR from the UE 200. If the Release Pending Timer is being activated (S101: Y), the process proceeds to step S102. On the other hand, if the Release Pending Timer is not activated (S101: N), the process proceeds to step S104.

  In step S102, the UE data retention amount management unit 140 determines whether DL / UL U-plane data for the UE 200 is generated within a predetermined period. If the occurrence of DL / UL U-plane data for the UE 200 is detected (S102: Y), the process proceeds to step S103. On the other hand, when the generation of DL / UL U-plane data for the UE 200 is not detected in a predetermined period (S102: N), the process ends with the RRC connected state with the UE 200 being maintained.

  In step S103, the Release Pending Timer 150 stops and resets the Release Pending Timer. Since generation of DL / UL U-plane data is detected in a state where the Release Pending Timer is not activated, the UE Inactive Timer management unit 160 stops and resets the UE Inactive Timer. Thereafter, this process ends while maintaining the RRC connected state with the UE 200.

  In step S104, the UE Inactive Timer manager 160 determines whether the UE Inactive Timer has passed a predetermined threshold. When the UE Inactive Timer exceeds the predetermined threshold (S104: Y), the process proceeds to step S105, and when the UE Inactive Timer does not exceed the predetermined threshold (S104: N), The process ends with maintaining the RRC connected state with the UE 200.

  In step S105, the UE state management unit 130 causes the UE 200 to transition to the idle state by transmitting an RRC connection Release to the UE 200.

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

10 wireless communication system 100 base station (eNB)
110 Downlink (DL) signal transmission unit 120 Uplink (UL) signal reception unit 130 UE state management unit 140 UE data retention amount management unit 150 Release Pending Timer management unit 160 UE Inactive Timer management unit 200 User equipment (UE)

Claims (7)

A base station that communicates with user equipment in a wireless communication system,
A data retention amount management unit for managing the amount of downlink and / or uplink data transmitted to and received from the user device;
A first timer management unit for managing a first timer for measuring a period during which downlink and uplink traffic data transmitted / received to / from the user apparatus is not generated;
A second timer management unit for managing a second timer that holds suspension and resetting of the first timer;
A user device state management unit that transitions the user device from a connection establishment state to an idle state when the first timer exceeds a predetermined threshold;
Have
The second timer management unit starts the second timer when receiving a message notifying that uplink data has been generated from the user apparatus, and receives the uplink traffic data from the user apparatus. Stop and reset the timer,
The first timer management unit is a base station that continues to activate the first timer while the second timer is activated.   The first timer management unit activates the first timer when there is no downlink or uplink traffic data transmitted to or received from the user apparatus, and sends a message notifying that uplink data has been generated from the user apparatus. 2. The base station according to claim 1, wherein upon reception, when the second timer is stopped and reset, the first timer is stopped and reset.   The message notifying that the uplink data has occurred is a buffer status report (BSR) in an LTE system, and notifies a total data amount of control data and traffic data transmitted from the user equipment. The listed base station. The control data is C-plane data in the LTE system,
The base station according to claim 3, wherein the traffic data is U-plane data in the LTE system.   The data retention amount management unit determines that the U-plane data has been generated by receiving U-plane data addressed to the user apparatus from a higher-level station of the base station, and receives the buffer status report from the user apparatus. 5. The base station according to claim 4, wherein the base station determines that the U-plane data has been generated by receiving an uplink MAC (Medium Access Control) PDU (Protocol Data Unit). A user device;
A base station communicating with the user equipment;
A wireless communication system comprising:
The base station
A data retention amount management unit for managing the amount of downlink and / or uplink data transmitted to and received from the user device;
A first timer management unit for managing a first timer for measuring a period during which downlink and uplink traffic data transmitted / received to / from the user apparatus is not generated;
A second timer management unit for managing a second timer that holds suspension and resetting of the first timer;
A user device state management unit that transitions the user device from a connection establishment state to an idle state when the first timer exceeds a predetermined threshold;
Have
The second timer management unit starts the second timer when receiving a message notifying that uplink data has been generated from the user apparatus, and receives the uplink traffic data from the user apparatus. Stop and reset the timer,
The first timer management unit is a wireless communication system in which the first timer continues to be activated while the second timer is activated. A method for controlling a connection state of a user apparatus by a base station of a wireless communication system,
Determining whether a second timer for suspending the stop and reset of the first timer for timing a period during which downlink and uplink traffic data transmitted and received to and from the user equipment is not generated is being activated;
When the second timer is running, upon receiving uplink traffic data from the user equipment, stopping and resetting the second timer and stopping and resetting the first timer;
When the second timer is not running, and when the first timer exceeds a predetermined threshold, transitioning the user apparatus from a connection establishment state to an idle state;
Having a method.

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