JP6239254B2 - Mobile communication system and handover transfer data wait control method - Google Patents

Description

  The present invention relates to a radio base station in a mobile communication system such as LTE, and particularly relates to a technique in which a radio base station waits for transfer data during handover.

  In the present specification and claims, “LTE” includes not only a communication system corresponding to Release 8 or 9 of 3GPP but also a communication system corresponding to Release 10, 11 or 12 of 3GPP. Used in.

  In LTE, when the user apparatus UE moves and the optimum cell for performing communication with the user apparatus UE in the RRC connected state (RRC connected state) changes, the user apparatus UE transitions to the optimum cell. The handover control to be performed is defined (3GPP TS36.300).

  FIG. 1 shows an overview of handover control in LTE. When a handover is performed, a handover source radio base station eNB (Source-eNB: S-eNB, hereinafter referred to as a source radio base station eNB) is a DL (downlink) whose delivery has not been confirmed by the source radio base station eNB. Data (DL PDCP PDU) and UL (uplink) data (UL PDCP PDU) received in the out-of-order at the source radio base station eNB (UL PDCP PDU) are transferred to the handover destination eNB (Target-eNB: T- Data transfer control to be transferred to an eNB (hereinafter referred to as a target radio base station eNB) is performed (A in FIG. 1).

  Further, in order to maintain the order of DL / UL data, the target radio base station eNB does not start transmission of new data received from an upper node (eg, Serving-Gateway) until all DL and UL transfer data are received ( B) in FIG.

  Here, the target radio base station eNB detects that all the DL / UL transfer data has been received as follows.

  Regarding the DL, the upper node transmits an end marker following the transfer data to the source radio base station eNB (C in FIG. 1) upon success of the handover (C in FIG. 1), and the route of the U-plane data is transmitted to the source radio base. Switching from the station eNB side to the target radio base station eNB side (Path switch, D in FIG. 1). The end marker is sent from the source radio base station eNB to the target radio base station eNB, and the target radio base station eNB determines that all DL transfer data has been received by receiving the end marker.

  Regarding the UL, during the handover procedure, an SN status transfer message (SN status transfer), which is an IE indicating the reception status of the UL PDCP PDU in the source radio base station eNB, is transmitted from the source radio base station eNB to the target radio base station eNB. The SN status transfer message includes information indicating reordering wait data, and the target radio base station eNB determines that all UL transfer data has been received by receiving all the reordering wait data.

3GPP TS 36.300

  In the transmission path between the source radio base station eNB and the target radio base station eNB, transfer data or end markers may be lost. For example, as shown in E of FIG. 2, when the end marker is missing, the target radio base station eNB cannot detect “all the transfer data has been received” indefinitely. In this case, since the target radio base station eNB cannot schedule new data from the upper node, generally, if it cannot detect that all the transfer data has been received even after a predetermined period of time, it gives up receiving the transfer data. Thus, control for starting scheduling of new data from the upper node is adopted (F in FIG. 2). The timer for measuring the predetermined period is called a transfer data wait timer.

  When performing the control with the transfer data waiting timer, the target radio base station eNB sets the predetermined period (=) to transfer the maximum amount of data that can be retained in the source radio base station eNB so that all transfer data can be received. Timer value).

  However, if the timer value is too long, scheduling of new data that reaches the target radio base station eNB from the upper node may be delayed when an end marker or the like is lost, which may cause problems such as a reduction in throughput.

  The present invention has been made in view of the above points. In handover of a user apparatus in a mobile communication system, when transferring data related to communication of the user apparatus from a source radio base station to a target radio base station, It is an object of the present invention to provide a technique that makes it possible to appropriately control a transfer data waiting time in a radio base station.

The present invention is a mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
The handover source radio base station is
A notification means for notifying the handover destination radio base station of information on the capability of the user apparatus, setting information, or a value of a UE inactivity timer when it is determined to cause the user apparatus to perform handover;
The handover destination radio base station is
Based on the capability information, setting information, or UE inactivity timer value received from the handover source radio base station, data related to communication of the user device is handed over from the handover source radio base station at the time of handover of the user device. Time estimation means for estimating the time taken to transfer to the handover destination radio base station;
The time estimated by the time estimation means is used as a value of a transfer data wait timer that measures the time to wait for completion of data transfer related to communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus. Means for setting,
The time estimation means estimates the presence / absence of data about the user apparatus in the handover source radio base station based on a value of a UE inactivity timer received from the handover source radio base station, and based on the presence / absence of the data It is configured as a mobile communication system and calculates the time.
Further, the present invention is a mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
The handover source radio base station is
A notification means for notifying the handover destination radio base station of information on the capability of the user apparatus, setting information, or a value of a UE inactivity timer when it is determined to cause the user apparatus to perform handover;
The handover destination radio base station is
Based on the capability information, setting information, or UE inactivity timer value received from the handover source radio base station, data related to communication of the user device is handed over from the handover source radio base station at the time of handover of the user device. Time estimation means for estimating the time taken to transfer to the handover destination radio base station;
The time estimated by the time estimation means is used as a value of a transfer data wait timer that measures the time to wait for completion of data transfer related to communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus. Means for setting,
When the handover source radio base station determines that the data retention amount for the user device in the handover source radio base station is larger than a predetermined threshold at the time of handover of the user apparatus, the handover destination radio base station A predetermined short time may be set as the value of the transfer data wait timer.
The time estimation means estimates a data retention amount for the user apparatus in the handover source radio base station corresponding to capability information or setting information received from the handover source radio base station, and based on the data retention amount The time may be calculated.

  The present invention can also be configured as a handover transfer data wait control method executed by each mobile communication system.

  According to the present invention, in user equipment handover in a mobile communication system, data related to communication of the user equipment is transferred from a source radio base station (handover source radio base station) to a target radio base station (handover destination radio base station). In this case, it is possible to appropriately control the transfer data waiting time in the target radio base station according to the transfer data amount.

It is a figure which shows the outline | summary of a hand-over. It is a figure which shows the case where an end marker is missing at the time of a handover. 1 is a configuration diagram of a mobile communication system according to an embodiment of the present invention. It is a figure which shows the example of the procedure of a hand-over. It is a figure for demonstrating the process example 1 in 1st Embodiment. It is a figure for demonstrating the process example 1 in 1st Embodiment. It is a figure for demonstrating the process example 2 in 1st Embodiment. It is a figure for demonstrating the process example 2 in 1st Embodiment. It is a functional block diagram of the radio base station eNB10 which concerns on embodiment of this invention. It is a flowchart which shows the example of a process sequence of the radio base station eNB10 in the process example 1 of 1st Embodiment. It is a flowchart which shows the example of a process sequence of the radio base station eNB10 in the process example 2 of 1st Embodiment. It is a flowchart which shows the example of a process sequence of the radio base station eNB10 in the process example 2 of 1st Embodiment. It is a figure for demonstrating the process example 1 in 2nd Embodiment. It is a figure for demonstrating the process example 2 in 2nd Embodiment. It is a figure for demonstrating UE inactivity timer. It is a flowchart which shows the example of a process sequence of the radio base station eNB10 in 2nd Embodiment. It is a figure for demonstrating a modification.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiment described below is only an example, and the embodiment to which the present invention is applied is not limited to the following embodiment. For example, below, LTE is used as an example of a mobile communication system, but the present invention is not limited to LTE and can be applied. Further, the handover method to which the present invention can be applied is not limited to the X2 interface method, and can be applied to other handover methods.

  FIG. 3 shows a configuration diagram of the mobile communication system according to the embodiment of the present invention. The mobile communication system according to the present embodiment is an LTE communication system, for example, and includes a source radio base station eNB1, a target radio base station eNB2, and a user apparatus UE as shown in FIG. FIG. 3 also shows a higher-level node UN (eg, Serving GW) connected to the source radio base station eNB1 and the target radio base station eNB2.

  In the present embodiment, the transfer data waiting timer is dynamically changed according to the amount of data staying in the source radio base station eNB1. For example, if the data retention amount is small, the scheduling delay can be suppressed when the end marker is missing by setting the transfer data wait timer to a small value.

  Hereinafter, the first embodiment and the second embodiment will be described. In this embodiment, the procedure of the X2 handover in LTE is used as an example. First, a general message about the handover is used. The flow will be described with reference to FIG.

  The user apparatus UE transmits a measurement report (Measurement Report) to the source radio base station eNB by using a predetermined event condition as a trigger (Step 1). The source radio base station eNB decides to perform handover from the radio field intensity included in the measurement report and starts the handover procedure.

  In the handover procedure, the source radio base station eNB transmits a handover request message (Handover Request) (Step 2), and the target radio base station eNB transmits a handover request ACK (Handover Request Acknowledgment) to the source radio base station eNB (Step Step). 3). The source radio base station eNB transmits an RRC connection reconfiguration message to the user apparatus UE (step 4). Further, the source radio base station eNB transmits the above-described SN status transfer message to the target radio base station eNB (step 5), and further, the data stored in the source radio base station eNB is transmitted to the target radio base station eNB. Transfer to station eNB (step 6). The user apparatus UE performs a random access (RA) procedure in order to connect to the target radio base station eNB (steps 7 and 8), and transmits an RRC connection reconfiguration complete message to the target radio base station eNB. (Step 9). Thereby, the target radio base station eNB recognizes the success of the handover, and if DL data is received from the source radio base station eNB, transmits the DL data to the user apparatus UE, and the user apparatus UE transmits UL to the target radio base station eNB. Data is transmitted (step 10).

  Further, the target radio base station eNB transmits a path switch request message for requesting the path to be switched to the target radio base station eNB side to the upper node (step 11). As a result, DL data is sent from the upper node to the target radio base station eNB (step 12). Further, a path switch request ACK (Path Switch Request Acknowledgment) is sent to the target radio base station eNB (step 13), and if there is UL data, the target radio base station eNB transmits to the upper node (step 14). Further, the target radio base station eNB transmits a UE context release message to the source radio base station eNB in order to release the context of the user apparatus UE in the source radio base station eNB (step 15).

  Note that RRC connection reconfiguration may be referred to as a handover (HO) command.

  Hereinafter, the first embodiment, the second embodiment, and modifications will be described.

(First embodiment)
<Processing content>
In the first embodiment, the source radio base station eNB or the target radio base station eNB calculates the value of the transfer data wait timer based on the data retention amount (transfer data amount) in the source radio base station eNB1.

  A processing example 1 in the first embodiment will be described with reference to FIGS. In Processing Example 1, the source radio base station eNB specifies a timer value for the target radio base station eNB during the handover procedure.

  In the example shown in FIG. 5, the source radio base station eNB1 calculates the value of the transfer data waiting timer based on the data retention amount at the time when the source radio base station eNB1 decides to perform handover (step 21), and uses the handover request message ( The value of the transfer data wait timer is notified to the target radio base station eNB2 (included in the handover request message) (step 22). The target radio base station eNB2 starts a transfer data waiting timer at the timing of transmitting the handover request ACK (step 23). The target radio base station eNB2 waits to receive all transfer data from the source radio base station eNB1 until the transfer data wait timer expires, and sends all transfer data to the source radio base before the transfer data wait timer expires. If it receives from station eNB1, the operation | movement of transferring the data from the high-order node UN to the user apparatus UE will be started at that time. If all the transfer data has not been received from the source radio base station eNB1 before the transfer data waiting timer expires, the data from the upper node UN is transferred to the user apparatus UE when the timer expires, etc. Start operation.

  Here, the data retention amount is the amount of data that remains in the source radio base station eNB and should be transferred to the target radio base station eNB2. Regarding the value of the transfer data wait timer, for example, the data retention amount / backhaul is calculated from the data retention amount and the backhaul bandwidth (the bandwidth (speed) of the line from the source radio base station eNB1 to the target radio base station eNB2). By calculating the bandwidth, an approximate value of the time required for data transfer is calculated as the value of the transfer data wait timer.

  Further, as illustrated in FIG. 6, the source radio base station eNB1 may transmit the calculated transfer data waiting timer value using the SN status transfer message (included in the SN status transfer message). In this case, the target radio base station eNB2 starts a transfer data wait timer when receiving the SN status transfer message.

  7 and 8 are diagrams for explaining a processing example 2 according to the first embodiment. In the processing example 2, as illustrated in FIG. 7, the source radio base station eNB1 notifies the target radio base station eNB of the staying data amount at the time of determining the handover using the handover request (Step 31). The base station eNB2 calculates the value of the transfer data wait timer by the method described above (data retention amount / backhaul band) (step 32), sets the value of the timer, and sets the timer when the handover request ACK is transmitted. Start (step 33).

  Further, as shown in FIG. 8, the source radio base station eNB1 notifies the target radio base station eNB of the staying data amount at the time of determining the handover using the SN status transfer message (step 31). The station eNB2 may calculate the value of the transfer data waiting timer by the method described above (step 32) and start the timer (step 33).

  If the target radio base station eNB2 receives neither the transfer data wait timer value nor the data retention amount in the handover request or the SN status transfer message, the target radio base station eNB2 uses the default value (fixed value) held in advance as the transfer data. It may be set as the value of the waiting timer.

<Apparatus configuration, processing flow>
FIG. 9 shows a functional configuration diagram of the radio base station eNB10 according to the embodiment of the present invention (common to the first and second embodiments). Since the radio base station eNB10 may operate as a source radio base station when viewed from the user apparatus UE or may operate as a target radio base station, the radio base station eNB illustrated in FIG. Both the function as the source radio base station of the embodiment and the function as the target radio base station of the embodiment of the present invention are provided.

  As illustrated in FIG. 9, the radio base station eNB10 includes a buffer management unit 11, a data transfer unit 12, a UE management unit 13, a handover processing unit 14, and a timer management unit 15. Note that FIG. 9 shows only functional units particularly relevant to the present invention in the radio base station eNB10, and also has a function (not shown) for performing at least the operation based on the LTE scheme.

  The buffer management unit 11 includes a data buffer 111 (memory or the like). The data buffer 111 stores UL data and DL data of the user apparatus UE. The buffer management unit 11 includes a function of calculating and outputting the staying amount of DL data and UL data stored in the data buffer 111.

  The data transfer unit 12 has a function of transferring data stored in the data buffer 111 to the target radio base station in the handover procedure. The handover processing unit 14 has a function of performing handover processing by performing transmission / reception of messages in handover. For example, when functioning as a source radio base station, the handover processing unit 14 acquires the UE state (configuration, context, etc.) from the UE management unit 13 in order to take over the state of the user apparatus UE to the target radio base station. And transmitted in a handover request message.

  The UE management unit 13 is a functional unit that manages the state of each user apparatus UE, and includes a UE state storage unit 131. The UE state storage unit stores capability information, state information, and the like of each user apparatus UE. The UE management unit 13 acquires the state of the user apparatus UE and stores the acquired state in the UE state storage unit 131. A function of acquiring and outputting a state and the like for a specific user apparatus UE from the UE state storage unit 131 is provided.

  The timer management unit 15 includes a transfer data waiting timer 151 and a timer value calculation unit 152 (an example of time estimation means). The transfer data wait timer 151 is a timer that has already been described, and is a timer that measures the time to wait for all transfer data from the source radio base station to be transferred when operating as the target radio base station. If this timer expires before all transfer data is transferred, the timer management unit 15 controls the handover processing unit 14 to transmit / receive new data without waiting for transfer data any more.

  The timer value calculation unit 152 has a function of calculating the value of the transfer data wait timer based on the data retention amount and the like.

  FIG. 10 is a flowchart illustrating a processing procedure example of the radio base station eNB10 in Processing Example 1 of the first embodiment. With reference to FIG. 10, a processing procedure of processing example 1 in the first exemplary embodiment will be described. When the handover processing unit 14 in the radio base station eNB10 as the source radio base station determines to perform handover for the user apparatus UE based on the measurement report from the user apparatus UE (Yes in Step 41), a timer value calculation section 152 acquires the data retention amount of the user apparatus UE from the buffer management unit 11, and calculates the value of the transfer data waiting timer from the data retention amount and the backhaul band (step 42).

  Then, the handover processing unit 14 notifies the target radio base station of the value of the transfer data wait timer using the handover request message or the SN status transfer message. In the target radio base station, a transfer data wait timer is set to the notified timer value (time).

  FIGS. 11 and 12 are flowcharts illustrating a processing procedure example of the radio base station eNB10 in the processing example 2 of the first embodiment. With reference to FIG. 11 and FIG. 12, the processing procedure of the processing example 2 in the first embodiment will be described.

  When the handover processing unit 14 in the radio base station eNB10 functioning as the source radio base station determines to perform handover for the user apparatus UE based on the measurement report from the user apparatus UE (Yes in Step 51), the handover processing section 14 acquires the data retention amount of the user apparatus UE from the buffer management unit 11, and notifies the target radio base station of the data retention amount using the handover request message or the SN status transfer message (step 52).

  When the radio base station eNB10 that functions as the target radio base station receives the data retention amount using the handover request message or the SN status transfer message (Yes in Step 53), the timer value calculation unit 152 The value of the transfer data waiting timer is calculated from the hole band (step 54), and the calculated timer value is set in the transfer data waiting timer (step 55).

(Second Embodiment)
In the second embodiment, the target radio base station eNB2 estimates the transfer data waiting timer value and sets the timer value.

<Processing content>
With reference to FIG. 13, the process example 1 in 2nd Embodiment is demonstrated. In this example, the target radio base station eNB2 calculates an appropriate timer value by estimating the data retention amount. In the example of FIG. 13, the source radio base station eNB1 notifies the target base station eNB2 of information indicating the capability of the user apparatus UE or information indicating configuration (configuration) of the user apparatus UE in the source radio base station eNB1 (step 61).

  Then, the target base station eNB2 estimates the data retention amount in the source radio base station eNB1 based on the capability or setting information, and calculates an approximate value of the time required for data transfer as a timer value (step 62). The calculated value is set as the value of the transfer data wait timer, and the transfer data wait timer is started (step 63). The method for calculating the timer value from the data retention amount is the same as in the first embodiment.

  In this example, it is assumed that the capability and setting information used for estimating the data retention amount is included in the handover request message. If not included, the information is included in the source radio base station eNB1. You may do it. Further, it is not essential to transmit the capability and setting information in the handover request message, but the information may be transmitted in another message (eg, SN status transfer message).

  Processing example 1 of the present embodiment is based on the assumption that a large amount of data is generated for the user apparatus UE that can achieve high throughput. That is, for example, in the case of TCP often used in data communication, it is assumed that the user apparatus UE that can achieve high throughput sets a large TCP window size in order to achieve a peak rate, and the larger the TCP window size is, the more wireless it is. The amount of data transmitted and received increases. Therefore, it can be assumed that a large amount of data is generated for the user apparatus UE that can achieve high throughput.

  In addition, since there are, for example, the capability of the user apparatus UE and the setting (configuration) for the user apparatus UE in the source radio base station eNB as elements related to the size of the throughput realized by the user apparatus UE, In the processing example 1, this information is notified to the target radio base station eNB2, the data retention amount is estimated in the target radio base station eNB2, the time required for data transfer is calculated, and the value of the transfer data wait timer is set It is said.

  Examples of information indicating the capability of the user apparatus UE in the processing example 1 include the UE category (capability classification of the user apparatus defined in the standard), the number of component carriers (CC) that can be aggregated in the carrier aggregation (CA), MIMO And how many layers are supported. The target radio base station eNB2 determines that the higher the capability of the user apparatus UE is, the higher the throughput can be achieved, and the higher the probability that the user apparatus UE is communicating at a high throughput. For example, when the capability 1 of the user apparatus UE is higher than the capability 2, the estimated data retention amount corresponding to the capability 1 is larger than the estimated data retention amount corresponding to the capability 2. For example, the target radio base station eNB2 holds a table in which the capability of the user apparatus UE and the estimated data retention amount are associated with each other in the storage unit, and determines the data retention amount by referring to the table.

  As an example of the setting in the source radio base station eNB1 for the user apparatus UE in the processing example 1, for example, there is a setting for the user apparatus UE capable of aggregating three component carriers to always operate with two component carriers. . The reason is, for example, that the optimal third CC cell was not found. Also, the number of MIMO layers (rank), transmission mode, etc. are examples of the above settings.

  The target radio base station eNB2 estimates the data retention amount according to the setting for the user apparatus UE. For example, when setting 1 (example: 3CC) of the user apparatus UE is a setting that can achieve higher throughput than setting 2 (example: 2CC), the estimated data retention amount corresponding to setting 1 is estimated corresponding to setting 2 Greater than data retention. For example, the target radio base station eNB2 holds a table in which the setting for the user apparatus UE and the estimated data retention amount are associated with each other in the storage unit, and determines the data retention amount by referring to the table.

  Note that no matter how high the capability of the user apparatus UE is, it is not possible to achieve high throughput unless it is set so that the capability can be fully utilized. It is preferable to estimate the data retention amount based on this.

  With reference to FIG. 14, the process example 2 in 2nd Embodiment is demonstrated. In this example, the source radio base station eNB1 notifies the target radio base station eNB2 of the value of a UE inactive timer (UE Inactive Timer) (step 71). Then, the target radio base station eNB2 determines the presence / absence of U-plane (user plane) data of the corresponding user apparatus in the source radio base station eNB1 based on the value of the UE inactivity timer, and according to the presence / absence of the data The transfer data wait timer value is calculated (step 72), set, and the transfer data wait timer is started (step 73).

  In this example, when the value of the UE inactivity timer is a value indicating that the UE inactivity timer is activated (a value other than 0, a value larger than a predetermined threshold, etc.), it is applicable in the source radio base station eNB1. In the source radio base station eNB1, when it is determined that there is residence data of the user apparatus UE, a transfer data waiting timer value is set when there is data, and the UE inactivity timer is not activated, It is determined that there is no accumulated data, and a transfer data wait timer value is set when there is no data. That is, in this example, the target radio base station eNB2 holds two values, a timer value for data presence and a timer value for no data, as transfer data wait timer values.

  In this example, it is assumed that the value of the UE inactivity timer used for estimation of whether there is data stagnation is included in the handover request message, but in the case where it is not included, the source radio base station eNB1 May be included. The UE inactivity timer value is not necessarily transmitted in the handover request message, but may be transmitted in another message (eg, SN status transfer message).

  Hereinafter, the UE inactivity timer will be described in more detail.

  In LTE applied to the present embodiment, the user apparatus UE is managed in two states: an RRC connected (RRC connected) state and an idle (IDLE) state.

The RRC connection state is a state in which connection is established by RRC, and is a state in which user data can be transmitted and received. It is desirable for a user having data to maintain an RRC connection state in order to transmit and receive data without delay.
The idle state is a state in which connection is not established by RRC, and when user data is transmitted and received, it is necessary to first establish a connection with the NW. A user who does not have data is desirably in an idle state from the viewpoint of battery saving and NW resources.
From the viewpoint of user response (delay), it is desirable that the user apparatus UE is in the RRC connection state. However, for the user apparatus UE that has no data for a predetermined period of time, it is assumed that no data will be generated and the user apparatus UE enters an idle state. Control for transition is performed.

  Under such state management, the radio base station eNB manages the UE inactivity timer for each user apparatus UE, and performs the following control. This control will be described with reference to FIG.

  When there is no U-plane data to be transmitted / received to / from the user apparatus UE, the radio base station eNB starts a UE inactivity timer (example: A and B in FIG. 15) and transmits / receives to / from the user apparatus UE. When the power U-plane data is generated, the UE inactivity timer is stopped (example: C in FIG. 15).

  In addition, when the UE inactivity timer expires (or exceeds the threshold), the radio base station eNB determines to perform idle transition for the user apparatus UE, and performs an RRC connection release (RRC connection release). Transmit (example: D in FIG. 15).

  In the case of handover or reconnection, the value of the timer is taken over to the target cell. This is because the user apparatus UE cannot easily make an idle transition if reset at every handover or reconnection.

  In Processing Example 2 of the present embodiment, when the value of the UE inactivity timer is a value indicating that the UE inactivity timer is not activated based on the control of the UE inactivity timer as described above (example: When it is estimated that there is data in the section C to B in FIG. 15 and the value of the UE inactivity timer is a value indicating that the UE inactivity timer is activated (example: section A to C in FIG. 15) ) Is assumed to have no data, and the value of the transfer data wait timer is set.

<Apparatus configuration, processing flow>
The functional configuration of the radio base station eNB10 according to the second embodiment is the same as the configuration of the radio base station eNB10 illustrated in FIG. However, in the present embodiment, the processing content of the timer value calculation unit 152 is different from that of the first embodiment.

  In the present embodiment, the timer value calculation unit 152 holds a table in which the capacity, settings, and the like of the user apparatus are associated with the data retention amount, and the capacity of the user apparatus UE notified from the source radio base station eNB, Based on the setting or the like, the data retention amount is determined by referring to the table, and the transfer data wait timer value is calculated from the data retention amount and the backhaul band. In addition, the timer value calculation unit 152 holds a table in which data presence / absence in the source radio base station eNB is associated with the timer value, and based on the value of the UE inactivity timer notified from the source radio base station eNB, the table The transfer data wait timer value is determined by referring to.

  FIG. 16 is a flowchart illustrating an example of a processing procedure of the radio base station eNB10 (when functioning as a target radio base station) in the second embodiment. With reference to FIG. 16, a processing procedure in the second embodiment will be described.

  The source radio base station eNB decides to perform handover, and sends a handover request message or SN status transfer message including the capability, setting, or UE inactivity timer value of the user equipment as the radio base station eNB10 (as the target radio base station) Function) and the handover processing unit 14 of the radio base station eNB10 receives this.

  In the radio base station eNB10, the timer value calculation unit 152 acquires the value of the capability, setting, or UE inactivity timer from the received message, and calculates the value of the transfer data wait timer based on the acquired value (step) 82) A transfer data waiting timer is set according to the calculated timer value (step 83).

(Modification)
In each embodiment described so far, as shown in FIG. 17, when handover occurs in the source radio base station eNB1 in a state where the data retention time is very long (or in a state where the data retention amount is very large). In some cases, before the data is transferred from the source radio base station eNB1, retransmission data of staying data (transfer data) has already been issued from the upper level (eg, TCP) and has reached the target radio base station eNB side. (A in FIG. 17).

  In that case, the data for which higher-order retransmission has already been started is transferred from the source radio base station eNB1 to the target radio base station eNB2, and is transferred from the target radio base station eNB2 to the user apparatus UE. It is not desirable from the viewpoint of waste of resources.

  Therefore, when it is detected that the data retention amount is larger than the predetermined threshold (or the data retention time is longer than the predetermined threshold) at the time when the handover is determined in the source radio base station eNB1, The base station eNB1 notifies the target radio base station eNB2 of a very short timer value (a predetermined short time) in a handover request or SN status transfer message, and the target radio base station eNB2 sets the timer value to a transfer data wait timer. Set as a value.

  Alternatively, when it is detected that the data retention amount is larger than the predetermined threshold (or the data retention time is longer than the predetermined threshold) at the time of determining the handover in the source radio base station eNB1, the source radio The base station eNB1 notifies the target radio base station eNB2 of information indicating that in a handover request or SN status transfer message, and the target radio base station eNB2 determines the very short timer value (predetermined short time). The timer value is set as the transfer data wait timer value.

  As a result, the target radio base station eNB2 transfers the already started retransmission data without waiting for the transfer data from the source radio base station eNB1. The processing of this modification can be applied to all the embodiments and processing examples described so far.

The following items are disclosed in the specification.
(Section 1)
A mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
The handover source radio base station is
When it is determined that the user apparatus is to be handed over, data related to communication of the user apparatus is transferred from the handover source radio base station when the user apparatus is handed over based on a data retention amount for the user apparatus. Time estimation means for estimating the time taken to transfer to the handover destination radio base station;
Means for notifying the handover destination radio base station of the time calculated by the time estimation means,
The handover destination radio base station is
A value of a transfer data wait timer that measures the time received from the handover source radio base station, and the time to wait for completion of data transfer related to the communication of the user device transferred from the handover source radio base station at the time of handover of the user device With means to set as
A mobile communication system.
(Section 2)
A mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
The handover source radio base station is
A notification means for notifying the handover destination radio base station of a data retention amount for the user apparatus when it is determined to cause the user apparatus to perform handover;
The handover destination radio base station is
Based on the data retention amount received from the handover source radio base station, it takes to transfer data related to communication of the user apparatus from the handover source radio base station to the handover destination radio base station at the time of handover of the user apparatus Time estimation means for estimating time;
The time estimated by the time estimation means is used as a value of a transfer data wait timer that measures the time to wait for completion of data transfer related to communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus. Means for setting,
A mobile communication system.
(Section 3)
The time estimation means calculates the time based on the data retention amount and a communication band from the handover source radio base station to the handover destination radio base station.
The mobile communication system according to item 1 or 2, characterized by the above.
(Section 4)
A mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
The handover source radio base station is
A notification means for notifying the handover destination radio base station of information on the capability of the user apparatus, setting information, or a value of a UE inactivity timer when it is determined to cause the user apparatus to perform handover;
The handover destination radio base station is
Based on the capability information, setting information, or UE inactivity timer value received from the handover source radio base station, data related to communication of the user device is handed over from the handover source radio base station at the time of handover of the user device. Time estimation means for estimating the time taken to transfer to the handover destination radio base station;
The time estimated by the time estimation means is used as a value of a transfer data wait timer that measures the time to wait for completion of data transfer related to communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus. Means for setting,
A mobile communication system.
(Section 5)
The time estimation means estimates a data retention amount for the user apparatus in the handover source radio base station corresponding to capability information or setting information received from the handover source radio base station, and based on the data retention amount Calculate the time
5. The mobile communication system according to item 4, wherein
(Section 6)
The time estimation means estimates the presence / absence of data about the user apparatus in the handover source radio base station based on a value of a UE inactivity timer received from the handover source radio base station, and based on the presence / absence of the data Calculate the time
5. The mobile communication system according to item 4, wherein
(Section 7)
When the handover source radio base station determines that the data retention amount for the user device in the handover source radio base station is larger than a predetermined threshold at the time of handover of the user apparatus, the handover destination radio base station Set a predetermined short time as the value of the transfer data wait timer
The mobile communication system according to any one of claims 1 to 6, wherein the mobile communication system is characterized in that
(Section 8)
A handover transfer data wait control method executed by a mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
When the handover source radio base station determines that the user apparatus is to be handed over, based on the data retention amount for the user apparatus, data related to communication of the user apparatus at the time of handover of the user apparatus A time estimation step for estimating a time required for transfer from the handover source radio base station to the handover destination radio base station;
The handover source radio base station notifying the handover destination radio base station of the time calculated in the time estimation step;
The time that the handover destination radio base station receives from the handover source radio base station, and waits for the completion of transfer of data related to the communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus A step of setting as a value of a transfer data wait timer for measuring
A handover transfer data wait control method comprising:
(Section 9)
A handover transfer data wait control method executed by a mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
A notification step of notifying the handover destination radio base station of a data retention amount for the user apparatus when the handover source radio base station determines to cause the user apparatus to perform a handover;
Based on the data retention amount received by the handover destination radio base station from the handover source radio base station, data related to communication of the user apparatus is transferred from the handover source radio base station to the handover destination radio at the time of handover of the user apparatus. A time estimation step for estimating the time taken to transfer to the base station;
The time estimated by the time estimation step is set as a value of a transfer data wait timer that measures the time to wait for completion of data transfer related to communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus. Steps to set,
A handover transfer data wait control method comprising:
(Section 10)
A handover transfer data wait control method executed by a mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
When the handover source radio base station decides to cause the user apparatus to perform handover, the user equipment capability information, setting information, or UE inactivity timer value is sent to the handover destination radio base station. A notification step to notify;
Based on capability information, setting information, or UE inactivity timer value received by the handover destination radio base station from the handover source radio base station, data related to communication of the user apparatus at the time of handover of the user apparatus A time estimation step for estimating a time required to transfer the handover from the handover source radio base station to the handover destination radio base station;
The handover destination radio base station waits for the time estimated by the time estimation step to wait for completion of transfer of data related to communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus. A step of setting as a value of the transfer data wait timer to be measured;
A handover transfer data wait control method comprising:
Although the modified examples, the embodiments, the modified examples, and the like have been described above, the disclosed invention is not limited to such embodiments and the like, and those skilled in the art will recognize various modified examples, modified examples, alternative examples, and substituted examples. Will understand. Although specific numerical examples have been described in order to facilitate understanding of the invention, these numerical values are merely examples and any appropriate values may be used unless otherwise specified. The classification of items in the above description is not essential to the present invention, and the items described in two or more items may be used in combination as necessary, or the items described in one item may be used in different items. It may be applied to the matters described in (if not inconsistent). The boundaries between functional units or processing units in the functional block diagram do not necessarily correspond to physical component boundaries. The operations of a plurality of functional units may be physically performed by one component, or the operations of one functional unit may be physically performed by a plurality of components. For convenience of explanation, the radio base station eNB has been described using a functional block diagram, but such an apparatus may be realized in hardware, software, or a combination thereof. Software operating in accordance with the present invention includes random access memory (RAM), flash memory, read only memory (ROM), EPROM, EEPROM, registers, hard disk (HDD), removable disk, CD-ROM, database, server and other suitable It may be stored in any storage medium. The present invention is not limited to the above embodiments, and various modifications, modifications, alternatives, substitutions, and the like are included in the present invention without departing from the spirit of the present invention.

eNB1 source radio base station eNB2 target radio base station eNB10 radio base station UE user equipment 11 buffer management unit 12 data transfer unit 13 UE management unit 14 handover processing unit 15 timer management unit 111 data buffer 131 UE state storage unit 151 transfer data wait timer 152 Timer value calculation unit

Claims (5)

A mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
The handover source radio base station is
A notification means for notifying the handover destination radio base station of information on the capability of the user apparatus, setting information, or a value of a UE inactivity timer when it is determined to cause the user apparatus to perform handover;
The handover destination radio base station is
Based on the capability information, setting information, or UE inactivity timer value received from the handover source radio base station, data related to communication of the user device is handed over from the handover source radio base station at the time of handover of the user device. Time estimation means for estimating the time taken to transfer to the handover destination radio base station;
The time estimated by the time estimation means is used as a value of a transfer data wait timer that measures the time to wait for completion of data transfer related to communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus. Means for setting ,
The time estimation means estimates the presence / absence of data about the user apparatus in the handover source radio base station based on a value of a UE inactivity timer received from the handover source radio base station, and based on the presence / absence of the data A mobile communication system, wherein the time is calculated .   A mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
  The handover source radio base station is
  A notification means for notifying the handover destination radio base station of information on the capability of the user apparatus, setting information, or a value of a UE inactivity timer when it is determined to cause the user apparatus to perform handover;
  The handover destination radio base station is
  Based on the capability information, setting information, or UE inactivity timer value received from the handover source radio base station, data related to communication of the user device is handed over from the handover source radio base station at the time of handover of the user device. Time estimation means for estimating the time taken to transfer to the handover destination radio base station;
  The time estimated by the time estimation means is used as a value of a transfer data wait timer that measures the time to wait for completion of data transfer related to communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus Means for setting,
  When the handover source radio base station determines that the data retention amount for the user device in the handover source radio base station is larger than a predetermined threshold at the time of handover of the user apparatus, the handover destination radio base station Set a predetermined short time as the value of the transfer data wait timer
  A mobile communication system. The time estimation means estimates a data retention amount for the user apparatus in the handover source radio base station corresponding to capability information or setting information received from the handover source radio base station, and based on the data retention amount The mobile communication system according to claim 2 , wherein the time is calculated. A handover transfer data wait control method executed by a mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
When the handover source radio base station decides to cause the user apparatus to perform handover, the user equipment capability information, setting information, or UE inactivity timer value is sent to the handover destination radio base station. A notification step to notify;
Based on capability information, setting information, or UE inactivity timer value received by the handover destination radio base station from the handover source radio base station, data related to communication of the user apparatus at the time of handover of the user apparatus A time estimation step for estimating a time required to transfer the handover from the handover source radio base station to the handover destination radio base station;
The handover destination radio base station waits for the time estimated by the time estimation step to wait for completion of transfer of data related to communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus. And setting as a value of the transfer data wait timer to be measured,
In the time estimation step, the handover destination radio base station estimates presence / absence of data on the user apparatus in the handover source radio base station based on a UE inactivity timer value received from the handover source radio base station Then, the handover transfer data wait control method, wherein the time is calculated based on the presence or absence of the data.   A handover transfer data wait control method executed by a mobile communication system having a handover source radio base station and a handover destination radio base station for causing a user apparatus to perform handover,
  When the handover source radio base station decides to cause the user apparatus to perform handover, the user equipment capability information, setting information, or UE inactivity timer value is sent to the handover destination radio base station. A notification step to notify;
  Based on capability information, setting information, or UE inactivity timer value received by the handover destination radio base station from the handover source radio base station, data related to communication of the user apparatus at the time of handover of the user apparatus A time estimation step for estimating a time required to transfer the handover from the handover source radio base station to the handover destination radio base station;
  The handover destination radio base station waits for the time estimated by the time estimation step to wait for completion of transfer of data related to communication of the user apparatus transferred from the handover source radio base station at the time of handover of the user apparatus. And setting as a value of the transfer data wait timer to be measured,
  When the handover source radio base station determines that the data retention amount for the user device in the handover source radio base station is larger than a predetermined threshold at the time of handover of the user apparatus, the handover destination radio base station Set a predetermined short time as the value of the transfer data wait timer
  A handover transfer data wait control method characterized by the above.

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