JP2015126349A - Method and apparatus for managing idle inactivity timer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contribute to reduction of management cost (including the paging cost) of a mobile terminal in which downlink traffic is generated frequently while staying in the idle state.SOLUTION: Network nodes (100, 200, or 300) determines the expiration period of idle inactivity time (101 or 301) used for determining the state transition of a mobile terminal (300) from the connected state to the idle state, based on the frequency of occurrence of downlink traffic addressed to the mobile terminal (300) while staying in the idle state.

Description

  The present application relates to mobile communication systems, and more particularly to management of idle inactivity timers.

  A multiple access mobile communication system shares wireless resources including at least one of time, frequency, and transmission power among multiple mobile terminals, so that multiple mobile terminals can perform wireless communication substantially simultaneously. It is possible to do. Typical multiple access schemes are Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or a combination thereof. The term mobile communication system used in this specification means a multiple access mobile communication system unless otherwise specified.

  The mobile communication system includes a mobile terminal and a network. The network includes a radio access network (RAN) and a core network. The mobile terminal communicates with an external network (for example, the Internet, a packet data network, or a private enterprise network) via the RAN and the core network. The mobile communication system is, for example, Universal Mobile Telecommunications System (UMTS) or Evolved Packet System (EPS) of 3rd Generation Partnership Project (3GPP). The RAN is, for example, Universal Terrestrial Radio Access Network (UTRAN) or Evolved UTRAN (E-UTRAN). The core network is, for example, a General Packet Radio Service (GPRS) packet core or an Evolved Packet Core (EPC).

  A mobile terminal generally transitions from an idle state to a connected state in order to perform communication. Then, after terminating the communication in the connected state, the mobile terminal transitions from the connected state to the idle state in response to the non-communication period in the connected state reaching a predetermined time. The definitions of the terms idle state and connected state used in the present specification and claims are as follows.

  The idle state is a state where the wireless connection between the mobile terminal and the base station is released. Accordingly, the base station does not have information (context) regarding idle mobile terminals. The position of the mobile terminal in the idle state is ascertained for each location registration area (e.g. tracking area or routing area) in the core network. The core network can reach idle mobile terminals by paging. Also, an idle mobile terminal cannot perform unicast data transfer with a base station. Therefore, an idle mobile terminal must transition to the connected state in order to perform unicast data transfer. Examples of idle states are (1) RRC idle state in UTRAN, (2) RRC_IDLE state in E-UTRAN, and (3) WiMAX (IEEE 802.16-2004), Mobile WiMAX (IEEE 802.16e-2005), and WiMAX2 ( Includes "Idle state" in IEEE 802.16m).

  On the other hand, the connected state is a state in which the mobile terminal is connected to the base station. Therefore, the base station holds information (context) regarding the mobile terminal in the connected state. The position of the mobile terminal in the connected state is grasped in cell units (base station units) in the core network of the public wireless communication network. In general, a connected mobile terminal can perform unicast data transfer with a base station. However, CELL_PCH state and URA_PCH state in UTRAN are states in which the context of the mobile terminal is held by the base station, but no dedicated channel is assigned to the mobile terminal in both uplink and downlink. Examples of connected states include (1) RRC connected state in UTRAN, (2) RRC_CONNECTED state in E-UTRAN, and (3) “Connected state” in WiMAX, mobile WiMAX and WiMAX2. The RRC connected state in UTRAN includes CELL_DCH state, CELL_FACH state, CELL_PCH state, and URA_PCH state.

  Connected mobile terminals, such as mobile WiMAX, UTRAN, and E-UTRAN mobile terminals, may perform discontinuous reception (DRX) for power saving. In E-UTRAN, DRX in the connected state is defined as a dormant mode (or DRX mode) in the RRC_CONNECTED state. In mobile WiMAX, DRX in the connected state is defined as a sleep mode in the connected state.

  A timer that measures a non-communication period in order to determine the state transition of the mobile terminal from the connected state to the idle state is called, for example, idle inactivity timer, RRC inactivity timer, or user inactivity timer. In this specification, this timer is referred to as idle inactivity timer. The idle inactivity timer may be managed by the base station, may be managed by the mobile terminal, or may be managed by both of them.

  It should be noted that the idle inactivity timer is distinguished from the timer (DRX inactivity timer) that measures the non-communication period in order to transition from the active mode to the DRX mode (sleep mode or dormant mode) in the connected state. It is. As already mentioned, the idle state is a state in which the radio connection (ie radio resource or RRC connection) between the base station and the mobile terminal is released, whereas the DRX mode in the connected state is The difference is that the wireless connection between the mobile terminals is maintained.

  Patent Documents 1 to 7 disclose that the expiration period of idle idle activity timer (also referred to as a timer value) is adjusted based on various indexes. In Patent Documents 1-7, the expiration period of idle inactivity timer is, for example, the type of mobile terminal, movement speed, movement frequency, communication frequency, communication period, communication interval, data amount per communication, traffic pattern, Transmission Control Protocol Port number included in (TCP) header or User Datagram Protocol (UDP) header, application program running on mobile terminal, remaining battery level, location of mobile terminal, time zone, type of radio access network to which mobile terminal is connected , Base station load, or core network device load.

JP 11-313370 A JP 2003-037874 A JP 2011-254377 A JP2013-143672A International Publication No. 2012/093433 International Publication No. 2012/093434 International Publication No. 2013/140743

  The present inventor has studied to adjust the expiration period of idle inactivity timer in consideration of the paging processing cost. As already described, the core network manages the positions of idle mobile terminals in units of location registration areas (e.g. tracking areas, routing areas) including a plurality of cells. The mobile core network performs paging within the paging area determined based on the location registration area when downlink traffic (ie, downlink data or incoming voice call) destined for an idle mobile terminal arrives. Send a signal. Here, it should be noted that the location registration area and the paging area determined based thereon generally include a plurality of cells and a plurality of base stations. Therefore, frequent paging for the mobile terminal not only increases the load of one base station that manages the cell in which the mobile terminal that should receive the paging is increased, but also loads of a plurality of base stations included in the paging area. There is a problem of increasing. For this reason, when determining the expiration period of idle inactivity timer applied to a mobile terminal, it is preferable to appropriately consider the occurrence frequency of paging for the mobile terminal.

  It should be noted that it may not be sufficient to determine the idle inactivity timer expiration period in consideration of the communication frequency (or network connection frequency) of the mobile terminal. Because mobile terminal communication is initiated spontaneously by the mobile terminal in response to the occurrence of uplink traffic (ie uplink data or outgoing voice call) at the mobile terminal, ie, without paging. Because there are things. The ratio of the case where communication is started in response to paging to the total communication count of the mobile terminal is considered to vary depending on the type, usage, time zone, user, or the like of the mobile terminal. Therefore, for example, simply determining the expiration period of the idle inactivity timer based on the number of occurrences or frequency of connection requests (eg RRC Connection Request or NAS Service Request) from the mobile terminal to the network, the paging processing cost is sufficient. May not be considered. In other words, the management cost (including the paging processing cost) of the mobile terminal that frequently generates downlink traffic while remaining in the idle state may not be sufficiently reduced.

  Patent Documents 1 to 7 disclose that the expiration period of idle inactivity timer is adjusted based on various indexes including the communication frequency of a mobile terminal, the load of a base station, and the load of a core network device. However, Patent Documents 1 to 7 do not disclose determining the expiration period of the idle inactivity timer of the mobile terminal by explicitly considering the paging processing cost.

  Accordingly, one of the objectives that the embodiments disclosed herein attempt to achieve is the administrative cost of mobile terminals (including paging processing costs) where downlink traffic occurs frequently while remaining idle. It is to provide a method, a network node, a base station, and a program that can contribute to the reduction of the network. Other objects or problems and novel features will become apparent from the description of the present specification or the accompanying drawings.

  In one embodiment, a method determines an expiration period of an idle inactivity timer used to determine a state transition of a mobile terminal from a connected state to an idle state, while the mobile terminal remains in the idle state. And determining based on the frequency of occurrence of downlink traffic addressed to the terminal.

  In one embodiment, the method includes: (a) setting an idle inactivity timer to an expiration period determined based on a frequency of occurrence of downlink traffic destined for the mobile terminal while the mobile terminal remains in an idle state; And (b) controlling the state transition of the mobile terminal from a connected state to an idle state using the idle inactivity timer.

  In one embodiment, the network node sets an expiration period of an idle inactivity timer used to determine the state transition of the mobile terminal from the connected state to the idle state, while the mobile terminal remains in the idle state. A determining unit configured for determining based on a frequency of occurrence of downlink traffic addressed to the mobile terminal;

  In one embodiment, the base station includes an idle inactivity timer and a setting unit. The idle inactivity timer is used to determine the state transition of the mobile terminal from the connected state to the idle state. The setting unit is configured to set, in the idle inactivity timer, an expiration period determined based on the frequency of occurrence of downlink traffic addressed to the mobile terminal while the mobile terminal remains in the idle state. .

  In one embodiment, the program includes a group of instructions for causing a computer to perform the control method. The control method uses an expiration period of an idle inactivity timer used to determine a state transition of a mobile terminal from a connected state to an idle state, while the mobile terminal is addressed to the mobile terminal while the mobile terminal remains in the idle state. Including determining based on the frequency of downlink traffic.

  According to the above-described embodiment, a method, a network node, and a method capable of contributing to a reduction in management cost (including paging processing cost) of a mobile terminal in which downlink traffic frequently occurs while remaining in an idle state, Base stations and programs can be provided.

It is a block diagram which shows the structural example of the mobile communication system which concerns on 1st Embodiment. It is a sequence diagram which shows operation | movement of the mobile communication system which concerns on 1st Embodiment. It is a block diagram which shows the structural example of the base station and movement management node which concern on 1st Embodiment. It is a block diagram which shows the structural example of the mobile communication system which concerns on 1st Embodiment. It is a sequence diagram which shows operation | movement of the mobile communication system which concerns on 2nd Embodiment. It is a block diagram which shows the structural example of the mobile terminal which concerns on 3rd Embodiment.

  Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted as necessary for clarification of the description.

<First Embodiment>
FIG. 1 is a block diagram illustrating a configuration example of a mobile communication system according to the present embodiment. The configuration example of FIG. 1 includes a radio access network (RAN) 10 and a core network 20. First, basic configurations and functions of the RAN 10 and the core network 20 will be described.

  The RAN 10 includes a base station 100. The base station 100 manages a cell and connects a radio connection (e.g. Radio Resource Control (RRC) connection) with a plurality of mobile terminals 300 using a radio access technology. The mobile terminal 300 has a radio interface, is connected to the RAN 10 by radio access technology, and is connected to the core network 20 via the RAN 10. The RAN 10 is, for example, E-UTRAN or UTRAN, or a combination thereof. In E-UTRAN, the base station 100 corresponds to Evolved NodeB (eNB). In UTRAN, the base station 100 corresponds to Radio Network Controller (RNC) and NodeB.

  In the example of FIG. 1, the base station 100 has an idle inactivity timer 101 and controls the state transition of the mobile terminal 300 from the connected state to the idle state. The idle inactivity timer 101 is used to determine the state transition of the mobile terminal 300 from the connected state to the idle state, and is an inactive state duration (ie, no communication period) during which user data related to the mobile terminal 300 is not transmitted or received. ). In the example of FIG. 1, idle inactivity timer 101 is arranged in base station 100 and started (restarted) by base station 100. The idle inactivity timer 101 may be arranged in another node arranged in the RAN 10.

  For example, the base station 100 starts (resumes) an idle inactivity timer of the mobile terminal 300 in response to scheduling of downlink or uplink radio resources to the mobile terminal 300. Instead of this, or in combination with this, the base station 100 receives, for example, downlink data addressed to the mobile terminal 300, transmits uplink grant to the mobile terminal 300, and paging to the mobile terminal 300. The idle inactivity timer of the mobile terminal 300 may be started (restarted) in response to at least one of message transmission and reception of a radio resource allocation request from the mobile terminal 300.

  When the idle inactivity timer 101 expires, the mobile terminal 300 transitions from the connected state to the idle state. For example, in response to the expiration of the idle inactivity timer 101, the base station 100 releases the bearer with the core network 20 related to the mobile terminal 300 to the core network 20 (specifically, the mobility management node 200). The request to the mobile terminal 300 (ie RRC connection) may be released. The mobile terminal 300 may transition from the connected state to the idle state in response to the release of the wireless connection (i.e. RRC connection) with the base station.

  The core network 20 is a network managed mainly by an operator who provides mobile communication services. The core network 20 is, for example, EPC in EPS, GPRS packet core in UMTS, or a combination thereof. The core network 20 has a control plane function including movement management and bearer management of the mobile terminal 300, and a user plane function including transfer of user data transmitted and received between the mobile terminal 300 and an external network. In the example of FIG. 1, the core network 20 includes a mobility management node 200 as a control plane entity. Although not shown, the core network 20 includes at least one forwarding node as a user plane entity. For example, in the case of UMTS, a forwarding node (not shown) includes a user plane function of a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN). In the case of EPS, the forwarding node includes a Serving Gateway (S-GW) and a Packet Data Network Gateway (P-GW).

  The mobility management node 200 performs mobility management and bearer management (e.g. bearer establishment, bearer configuration change, bearer release) of the mobile terminal 300. For example, in the case of UMTS, the mobility management node 200 has an SGSN control plane function. In the case of EPS, the mobility management node 200 has a function of MME (Mobility Management Entity). The mobility management node (eg MME) 200 is connected to a plurality of base stations (eg eNB) 100 by a control interface (eg S1-MME interface), and by a forwarding node (eg S-GW) and a control interface (eg S11 interface). Connected. The mobility management node 200 is responsible for exchanging Non-Access Stratum (NAS) messages between the mobile terminal 300 and the core network 20. The NAS message is a control message that is not terminated at the RAN 10 and is transparently transmitted and received between the mobile terminal 300 and the core network 20 without depending on the radio access scheme of the RAN 10. For example, the mobility management node 200 requests the base station 100 to set up a bearer with the core network 20 and a radio bearer with the mobile terminal 300 in response to receiving a service request message for resource allocation from the mobile terminal 300. To do.

  Subsequently, the determination of the expiration period of the idle inactivity timer 101 according to the present embodiment will be described below. In this embodiment, the expiration period of idle inactivity timer 101 applied to the mobile terminal 300 is determined based on the frequency of occurrence of downlink traffic addressed to the mobile terminal 300 while the mobile terminal 300 remains in the idle state. Is done. The expiration period of idle inactivity timer 101 is determined for each mobile terminal 300. The frequency of occurrence of downlink traffic addressed to the mobile terminal 300 while the mobile terminal 300 remains in an idle state can be rephrased as the frequency of occurrence of paging for the mobile terminal 300. In addition, the occurrence frequency of the downlink traffic can be rephrased as the occurrence frequency of an incoming call to the mobile terminal 300. The incoming call here includes not only a voice call but also data traffic.

  The expiration period of idle inactivity timer 101 applied to mobile terminal 300 may be determined to become longer as the frequency of occurrence of paging for mobile terminal 300 increases. For example, the expiration period of idle inactivity timer 101 is a first value at which the occurrence frequency of paging for mobile terminal 300 is relatively large, and is a second value at which the occurrence frequency of paging is relatively small. The expiration period is determined to be shorter than that. That is, a relatively long idle inactivity timer 101 expiration period is applied to the mobile terminal 300 having a high paging occurrence frequency. According to such an operation, it is possible to reduce the management cost (including the paging processing cost) of the mobile terminal 300 that frequently generates downlink traffic while remaining in the idle state. This is because by increasing the expiration period of idle inactivity timer 101, the time during which mobile terminal 300 stays in the connected state becomes longer, and thus the frequency of occurrence of paging is reduced.

  Furthermore, when determining the expiration period of idle inactivity timer 101 applied to mobile terminal 300, the number of base stations in the paging area to which mobile terminal 300 belongs may be considered. Specifically, the expiration period of idle inactivity timer 101 applied to mobile terminal 300 may be determined so as to increase as the number of base stations in the paging area to which mobile terminal 300 belongs increases. It can be said that the larger the number of base stations in the paging area to which the mobile terminal 300 belongs, the higher the paging processing cost of the mobile terminal 300 is. This is because frequent paging on the mobile terminal 300 not only increases the load on one base station where the mobile terminal 300 that should receive the paging is located, but also increases the load on all the multiple base stations included in the paging area. This is to increase it. Accordingly, by considering the number of base stations in the paging area, the paging processing cost of the mobile terminal 300 can be more accurately reflected in the expiration period of the idle inactivity timer 101. Note that the number of base stations in the paging area to which the mobile terminal 300 belongs can also be referred to as the number of base stations in the location registration area to which the mobile terminal 300 belongs. This is because the paging area is determined based on the location registration area, and the size of the paging area reflects the size of the location registration area.

  The determination of the expiration period of the idle inactivity timer 101 described above may be performed by the base station 100 in one example. In this case, the base station 100 receives from the core network 20 (eg, the mobility management node 200) a message indicating the frequency of occurrence of downlink traffic (in other words, the frequency of occurrence of paging) while the mobile terminal 300 is in the idle state. May be. Furthermore, the base station 100 may receive a message indicating the number of base stations in the paging area to which the mobile terminal 300 belongs from the core network 20 (e.g. mobility management node 200). The base station 100 determines the frequency of paging and the number of base stations in the paging area in a control procedure involving the mobile terminal 300 transitioning to a connected state, for example, an attach procedure or a service request procedure (bearer setting procedure) of the mobile terminal 300. May be received from the mobility management node 200.

  Alternatively, the expiration period of idle inactivity timer 101 may be determined in a core network node arranged in core network 20. In this case, the core network node (eg mobility management node 200) sends a message indicating the expiration period of idle inactivity timer 101 applied to the mobile terminal 300 to the base station having a radio connection (eg RRC connection) with the mobile terminal 300 100 may be transmitted. The core network node (eg, the mobility management node 200), in a control procedure involving the mobile terminal 300 transitioning to the connected state, for example, an attach procedure or a service request procedure (bearer setting procedure) of the mobile terminal 300, A message indicating the expiration period of idle inactivity timer 101 to be applied may be transmitted to base station 100.

  FIG. 2 is a sequence diagram illustrating an example of a procedure for updating the expiration period of idle inactivity timer 101 applied to mobile terminal 300. In the example of FIG. 2, the base station 100 has an idle inactivity timer 101 and determines an expiration period of the idle inactivity timer 101. In step S11, the mobility management node 200 transmits a message indicating the frequency of occurrence of downlink traffic for the mobile terminal 300 in the idle state (i.e. frequency of occurrence of paging for the mobile terminal 300) to the base station 100. In step S <b> 12, the base station 100 determines the expiration period of the idle inactivity timer 101 applied to the mobile terminal 300 based on the occurrence frequency of paging for the mobile terminal 300 notified from the mobility management node 200. In step S13, the base station 100 sets the determined expiration period in the idle inactivity timer 101, and controls the transition of the mobile terminal 300 from the connected state to the idle state using the idle inactivity timer 101.

  In step S11, the mobility management node 200 may further notify the base station 100 of the number of base stations in the paging area to which the mobile terminal 300 belongs. In step S12, the base station 100 considers both the occurrence frequency of paging for the mobile terminal 300 and the number of base stations in the paging area to which the mobile terminal 300 belongs, and the idle inactivity timer applied to the mobile terminal 300. An expiration period of 101 may be determined.

  Subsequently, configuration examples of the base station 100 and the mobility management node 200 will be described below. FIG. 3 is a block diagram illustrating a configuration example of the base station 100 and the mobility management node 200. The mobility management node 200 shown in FIG. 3 includes a terminal information management unit 201 and a paging frequency measurement unit 202. The terminal information management unit 201 manages information necessary for mobility management of the mobile terminal 300 in the idle state. Information necessary for this mobility management includes information indicating a location registration area (e.g. tracking area, routing area) to which the mobile terminal 300 belongs. The information necessary for this mobility management may include information indicating a paging area determined based on the location registration area to which the mobile terminal 300 belongs. The mobility management node 200 can obtain the number of base stations in the paging area to which the mobile terminal 300 belongs based on the information managed by the terminal information management unit 201.

  The paging frequency measurement unit 202 measures the occurrence frequency of paging for the mobile terminal 300. In other words, the paging frequency measurement unit 202 measures the frequency of occurrence of downlink traffic for the mobile terminal 300 while the mobile terminal 300 remains in an idle state. The paging frequency measurement unit 202 may be connected to a subscriber server not shown. The subscriber server is a database that holds subscriber data of the mobile terminal 300, and corresponds to, for example, a Home Subscriber Server (HSS) or a Home Location Register (HLR). In response to the mobile terminal 300 detaching from the core network 20, the paging frequency measurement unit 202 may save the paging frequency information related to the mobile terminal 300 measured by the paging frequency measurement unit 202 to the subscriber server. . Then, the paging frequency measurement unit 202 may read the paging frequency information from the subscriber server when the mobile terminal 300 attaches to the core network 20. By such an operation, the paging frequency measurement unit 202 can measure the paging frequency of the mobile terminal 300 that repeats attachment and detachment over a long period of time.

  The base station 100 illustrated in FIG. 3 includes an idle inactivity timer 101, a determination unit 102, and a setting unit 103. The idle inactivity timer 101 is used in the base station 100 to control the state transition of the mobile terminal 300 from the connected state to the idle state. The determination unit 102 receives the paging occurrence frequency for the mobile terminal 300 and the number of base stations in the paging area to which the mobile terminal 300 belongs from the mobility management node 200 (the terminal information management unit 201 and the paging frequency measurement unit 202). And the determination part 102 determines the expiration period of the idle inactivity timer 101 applied to the mobile terminal 300 based on such information. The setting unit 103 sets the expiration period determined by the determination unit 102 in the idle inactivity timer 101.

  As already described, in the case of UMTS, the base station 100 shown in FIG. 1 includes functions of RNC and NodeB. FIG. 4 shows a configuration example of a UMTS network. As shown in FIG. 4, the idle inactivity timer 101 may be arranged in the RNC. The mobility management node 200 in FIG. 4 corresponds to the SGSN control plane function.

  Subsequently, a specific example of determining the expiration period of idle inactivity timer 101 will be further described below. The base station 100 determines the expiration period of the idle inactivity timer 101 by further using another index different from the index described in the present embodiment (ie paging occurrence frequency and the number of base stations in the paging area). Also good. In other words, reducing the frequency of occurrence of paging for the mobile terminal 300 is only one of the goals in the optimization process for the expiration period of the idle inactivity timer 101.

  The base station 100 optimizes the expiration period of the idle inactivity timer 101 so as to reduce the management cost (including the paging processing cost) of the mobile terminal 300 using a plurality of indexes including the indexes described in the present embodiment. Also good. For example, the base station 100 uses the objective function related to the paging processing cost based on the indices described in this embodiment (ie paging occurrence frequency and the number of base stations in the paging area) and other management costs (eg connection / disconnection). A synthetic objective function (cost function) defined by a weighted sum of objective functions related to processing costs and handover processing costs may be used. Then, the base station 100 may determine the expiration period of the idle inactivity timer 101 so as to minimize this synthesis objective function.

  For example, the base station 100 may further consider the frequency of occurrence of connection / disconnection of the mobile terminal 300 (in other words, the frequency of occurrence of state transition between the idle state and the connected state). The frequency of connection / disconnection of the mobile terminal 300 is an index representing the connection / disconnection processing cost. The base station 100 may extend the expiration period of the idle inactivity timer 101 as the frequency of connection / disconnection of the mobile terminal 300 increases.

  Further, in determining the expiration period of idle inactivity timer 101, base station 100 may further consider the frequency of occurrence of handover of mobile terminal 300. Handover means movement between cells (or movement between base stations) of a mobile terminal 300 in a connected state. The frequency of occurrence of handover of the mobile terminal 300 is an index representing the handover processing cost. The base station 100 may shorten the expiration period of the idle inactivity timer 101 as the frequency of handover of the mobile terminal 300 increases.

  Furthermore, in determining the expiration period of idle inactivity timer 101, base station 100 may consider other various indexes described in Patent Documents 1-7.

<Second Embodiment>
In the present embodiment, a modification of the first embodiment will be described. As already described, the expiration period of idle inactivity timer 101 may be determined in a core network node (eg, mobility management node 200) arranged in core network 20 such as mobility management node 200.

  FIG. 5 is a sequence diagram illustrating a case where the expiration period of idle inactivity timer 101 is determined by mobility management node 200. In step S <b> 21, the mobility management node 200 determines the expiration period of the idle inactivity timer 101 to be applied to the mobile terminal 300 based on the occurrence frequency of paging for the mobile terminal 300. The mobility management node 200 may further consider the number of base stations in the paging area to which the mobile terminal 300 belongs in determining the expiration period of the idle inactivity timer 101.

  In step S22, the mobility management node 200 transmits a timer update request message to the base station 100. The timer update request message indicates the identifier of the target mobile terminal 300 and the expiration period of idle inactivity timer 101 determined in step S21. In step S23, the base station 100 updates the expiration period (timer value) of the idle inactivity timer 101 applied to the mobile terminal 300 in response to the request message from the mobility management node 200.

<Third Embodiment>
The mobile terminal 300 may have an idle inactivity timer in order to determine spontaneously the transition from the connected state to the idle state. The technical idea described in the first and second embodiments can also be used to determine the expiration period of the idle inactivity timer arranged in the mobile terminal 300. FIG. 6 shows a configuration example of the mobile terminal 300 including the idle inactivity timer 301. The determination unit 302 determines the expiration period of the idle inactivity timer 301 based on the occurrence frequency of paging for the mobile terminal 300. The occurrence frequency of paging may be measured by the mobile terminal 300 itself by monitoring the paging received by the mobile terminal 300. The setting unit 303 sets the expiration period determined by the determination unit 302 in the idle inactivity timer 301.

<Other embodiments>
In the first to third embodiments, description has been made mainly using specific examples related to EPS and UMTS. However, these embodiments apply to other mobile communication systems such as 3GPP2 CDMA2000 system (1xRTT, High Rate Packet Data (HRPD)), Global System for Mobile communications (GSM) / General packet radio service (GPRS) system, mobile It may be applied to a WiMAX system or the like.

  The method for determining the expiration period of the idle inactivity timer described in the first to third embodiments and the method for controlling the state transition of the mobile terminal using the idle inactivity timer include at least one processor (eg, a microprocessor, It may be realized by causing a computer system including a micro processing unit (MPU) and a central processing unit (CPU) to execute a program. Specifically, one or a plurality of programs including a group of instructions for causing the computer system to perform the algorithm described with reference to FIGS. 2 and 5 and the like may be supplied to the computer system.

  This program can be stored using various types of non-transitory computer readable media and supplied to a computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (eg flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (eg magneto-optical discs), compact disc read only memory (CD-ROM), CD-ROMs. R, CD-R / W, and semiconductor memory (for example, mask ROM, programmable ROM (PROM), erasable PROM (EPROM), flash ROM, random access memory (RAM)) are included. The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

  Furthermore, the above-described embodiment is merely an example relating to application of the technical idea obtained by the present inventors. That is, the technical idea is not limited to the above-described embodiment, and various changes can be made.

  For example, a part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.

(Appendix 1)
The generation of downlink traffic addressed to the mobile terminal while the mobile terminal remains in the idle state for the expiration period of the idle inactivity timer used to determine the state transition of the mobile terminal from the connected state to the idle state Comprising determining based on frequency,
Method.

(Appendix 2)
The method according to claim 1, wherein the determining includes increasing the expiration period as the occurrence frequency increases.

(Appendix 3)
The method according to claim 1 or 2, wherein the determining includes determining the expiration period based on the number of base stations in a paging area to which the mobile terminal belongs in addition to the occurrence frequency.

(Appendix 4)
The method according to claim 3, wherein the determining includes increasing the expiration period as the number of base stations increases.

(Appendix 5)
The method according to any one of appendices 1 to 4, wherein the occurrence frequency is represented by an occurrence frequency of paging for the mobile terminal.

(Appendix 6)
Measuring the occurrence frequency by a core network node; and notifying the occurrence frequency from the core network node to a base station;
Further comprising
The determining includes determining the expiration period by the base station;
The method according to any one of appendices 1 to 5.

(Appendix 7)
The determining includes determining the expiration period by a core network node;
The method further comprises notifying the expiration period from the core network node to a radio access network node that manages the idle inactivity timer.
The method according to any one of appendices 1 to 5.

(Appendix 8)
The method according to any one of appendices 1 to 7, further comprising setting the expiration period to the idle inactivity timer.

(Appendix 9)
The idle period determined based on the frequency of occurrence of downlink traffic destined for the mobile terminal while the mobile terminal remains in the idle state is set in the idle inactivity timer, and the idle state is connected using the idle inactivity timer. Controlling the state transition of the mobile terminal from the idle state to the idle state;
A method for controlling state transition of a mobile terminal.

(Appendix 10)
The method according to claim 9, wherein the expiration period is determined to become longer as the occurrence frequency increases.

(Appendix 11)
The method according to appendix 9 or 10, wherein the expiration period is determined based on the number of base stations in a paging area to which the mobile terminal belongs in addition to the occurrence frequency.

(Appendix 12)
The method according to claim 11, wherein the expiration period is determined to be longer as the number of base stations increases.

(Appendix 13)
The method according to any one of appendices 9 to 12, wherein the occurrence frequency is represented by an occurrence frequency of paging for the mobile terminal.

(Appendix 14)
The generation of downlink traffic addressed to the mobile terminal while the mobile terminal remains in the idle state for the expiration period of the idle inactivity timer used to determine the state transition of the mobile terminal from the connected state to the idle state A network node comprising a determining unit that determines based on a frequency.

(Appendix 15)
The network node according to appendix 14, wherein the determination unit determines the expiration period so that the expiration period is lengthened as the occurrence frequency increases.

(Appendix 16)
The network node according to appendix 14 or 15, wherein the determination unit determines the expiration period based on the number of base stations in a paging area to which the mobile terminal belongs in addition to the occurrence frequency.

(Appendix 17)
The network node according to appendix 16, wherein the determining unit determines the expiration period so that the expiration period is lengthened as the number of base stations increases.

(Appendix 18)
The network node according to any one of appendices 14 to 17, wherein the occurrence frequency is represented by an occurrence frequency of paging for the mobile terminal.

(Appendix 19)
An idle inactivity timer used to determine the state transition of the mobile terminal from the connected state to the idle state;
A setting unit that sets an expiration period determined based on an occurrence frequency of downlink traffic addressed to the mobile terminal while the mobile terminal remains in the idle state in the idle inactivity timer;
A base station comprising:

(Appendix 20)
The base station according to supplementary note 19, wherein the expiration period is determined to become longer as the frequency of occurrence increases.

(Appendix 21)
The base station according to appendix 19 or 20, wherein the expiration period is determined based on the number of base stations in the paging area to which the mobile terminal belongs in addition to the occurrence frequency.

(Appendix 22)
The base station according to appendix 21, wherein the expiration period is determined to become longer as the number of base stations increases.

(Appendix 23)
The base station according to any one of appendices 19 to 22, wherein the occurrence frequency is represented by an occurrence frequency of paging for the mobile terminal.

(Appendix 24)
The base station according to any one of appendices 19 to 23, further comprising a determination unit that receives a notification indicating the occurrence frequency from a core network node and determines the expiration period.

(Appendix 25)
The base station according to appendix 21 or 22, further comprising a determination unit that receives a notification indicating the occurrence frequency and the number of base stations from a core network node, and determines the expiration period.

(Appendix 26)
The base station according to any one of appendices 19 to 23, wherein the setting unit receives the expiration period from a core network node.

(Appendix 27)
A program for causing a computer to perform a control method,
The control method uses an expiration period of an idle inactivity timer used to determine a state transition of a mobile terminal from a connected state to an idle state, while the mobile terminal is addressed to the mobile terminal while the mobile terminal remains in the idle state. Including making decisions based on the frequency of downlink traffic,
program.

10 Radio access network (RAN)
20 Mobile core network 100 Base station 101 idle inactivity timer
102 decision unit 103 setting unit 200 mobility management node 201 terminal information management unit 202 paging frequency measurement unit 300 mobile terminal 301 idle inactivity timer
302 Determination unit 303 Setting unit

Claims (15)

The generation of downlink traffic addressed to the mobile terminal while the mobile terminal remains in the idle state for the expiration period of the idle inactivity timer used to determine the state transition of the mobile terminal from the connected state to the idle state Comprising determining based on frequency,
Method.   The method of claim 1, wherein the determining includes increasing the expiration period as the frequency of occurrence increases.   The method according to claim 1 or 2, wherein the determining includes determining the expiration period based on the number of base stations in a paging area to which the mobile terminal belongs in addition to the occurrence frequency.   4. The method of claim 3, wherein the determining includes lengthening the expiration period as the number of base stations increases.   The method according to any one of claims 1 to 4, wherein the occurrence frequency is represented by an occurrence frequency of paging for the mobile terminal. Measuring the occurrence frequency by a core network node; and notifying the occurrence frequency from the core network node to a base station;
Further comprising
The determining includes determining the expiration period by the base station;
The method of any one of claims 1-5. The determining includes determining the expiration period by a core network node;
The method further comprises notifying the expiration period from the core network node to a radio access network node that manages the idle inactivity timer.
The method of any one of claims 1-5.   The method according to claim 1, further comprising setting the expiration period to the idle inactivity timer. The idle period determined based on the frequency of occurrence of downlink traffic destined for the mobile terminal while the mobile terminal remains in the idle state is set in the idle inactivity timer, and the idle state is connected using the idle inactivity timer. Controlling the state transition of the mobile terminal from the idle state to the idle state;
A method for controlling state transition of a mobile terminal.   The method according to claim 9, wherein the expiration period is determined to increase as the occurrence frequency increases.   The generation of downlink traffic addressed to the mobile terminal while the mobile terminal remains in the idle state for the expiration period of the idle inactivity timer used to determine the state transition of the mobile terminal from the connected state to the idle state A network node comprising a determining unit that determines based on a frequency.   The network node according to claim 11, wherein the determination unit determines the expiration period so that the expiration period becomes longer as the occurrence frequency increases. An idle inactivity timer used to determine the state transition of the mobile terminal from the connected state to the idle state;
A setting unit that sets an expiration period determined based on an occurrence frequency of downlink traffic addressed to the mobile terminal while the mobile terminal remains in the idle state in the idle inactivity timer;
A base station comprising:   The base station according to claim 13, wherein the expiration period is determined to become longer as the occurrence frequency increases. A program for causing a computer to perform a control method,
The control method uses an expiration period of an idle inactivity timer used to determine a state transition of a mobile terminal from a connected state to an idle state, while the mobile terminal is addressed to the mobile terminal while the mobile terminal remains in the idle state. Including making decisions based on the frequency of downlink traffic,
program.

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