JP2012109640A - Mobile communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption of a mobile terminal by reducing an opportunity for a mobile terminal to receive notification information of a new cell by suppressing cell re-selection.SOLUTION: In a mobile communication system of the invention, a mobile terminal determines mobile state information indicating the mobile state of the mobile terminal based on the number of times of cell selection performed in a certain period, and performs cell selection based on the mobile state information and a parameter for controlling cell selection notified by a base station. The mobile terminal operates to add a count to the number of times of cell selection if a selected cell is a macro cell, and not to add the count to the number of times of cell selection if the selected cell is a closed subscriber group (CSG) cell.

Description

  The present invention relates to a mobile communication system in which a base station performs wireless communication with a plurality of mobile terminals.

  Among the communication systems called the third generation, the W-CDMA (Wideband Code division Multiple Access) system has been commercialized in Japan since 2001. Also, by adding a packet transmission channel (HS-DSCH: High Speed-Downlink Shared Channel) to the downlink (dedicated data channel, dedicated control channel), further speeding up data transmission using the downlink Realized HSDPA (High Speed Down Link Packet Access) service has been started. Furthermore, in order to further increase the speed of data transmission in the uplink direction, a service has also started for the HSUPA (High Speed Up Link Packet Access) method. W-CDMA is a communication system defined by 3GPP (3rd Generation Partnership Project), which is a standardization organization for mobile communication systems, and has compiled release 8 standards.

  In 3GPP, as a communication method different from W-CDMA, “Long Term Evolution LTE” for the radio section and the entire system configuration including the core network (also simply referred to as network) are “System”. A new communication method called "Architecture Evolution SAE" is being studied. In LTE, the access scheme, radio channel configuration and protocol are completely different from those of the current W-CDMA (HSDPA / HSUPA). For example, while W-CDMA uses Code Division Multiple Access, W-CDMA uses OFDM (Orthogonal Frequency Division Multiplexing) in the downlink direction and SC-FDMA (Single in the uplink direction). Career Frequency Division Multiple Access) is used. The bandwidth is selectable for each base station within 1.4 / 3/5/10/15/20 MHz in LTE, whereas W-CDMA is 5 MHz. Also, LTE does not include circuit switching as in W-CDMA, and is only a packet communication system.

  LTE is defined as an independent radio access network different from the W-CDMA network because the communication system is configured using a new core network different from the W-CDMA core network (GPRS). Therefore, in order to distinguish from a W-CDMA communication system, in an LTE communication system, a base station (Base station) that communicates with a mobile terminal (UE: User Equipment) is an eNB (E-UTRAN NodeB), and a plurality of base stations. A base station controller (Radio Network Controller) that exchanges control data and user data with each other is called an EPC (Evolved Packet Core) (sometimes called an aGW: Access Gateway). In the LTE communication system, a unicast service and an E-MBMS service (Evolved Multimedia Broadcast Multicast Service) are provided. The E-MBMS service is a broadcast-type multimedia service and may be simply referred to as MBMS. Mass broadcast contents such as news, weather forecasts, and mobile broadcasts are transmitted to a plurality of mobile terminals. This is also called a point-to-multipoint service.

  Non-Patent Document 1 describes the current decisions regarding the overall architecture of the LTE system in 3GPP. The overall architecture (Chapter 4 of Non-Patent Document 1) will be described with reference to FIG. FIG. 1 is an explanatory diagram illustrating a configuration of an LTE communication system. In FIG. 1, a control protocol (for example, RRC (Radio Resource Management)) and a user plane (for example, PDCP: Packet Data Convergence Protocol, RLC: Radio Link Control, MAC: Medium Access Control, PHY: Physical layer) for the mobile terminal 101 are based. If terminated at station 102, Evolved Universal Terrestrial Radio Access (E-UTRAN) is composed of one or more base stations 102. The base station 102 performs scheduling (Scheduling) and transmission of a paging signal (also referred to as a paging message or paging message) notified from the MME 103 (Mobility Management Entity). Base stations 102 are connected to each other via an X2 interface. The base station 102 is connected to the EPC (Evolved Packet Core) via the S1 interface. More specifically, the base station 102 is connected to the MME 103 (Mobility Management Entity) via the S1_MME interface, and is connected to the S-GW 104 (Serving Gateway) via the S1_U interface. The The MME 103 distributes the paging signal to a plurality or a single base station 102. Further, the MME 103 performs mobility control (Mobility control) in an idle state. The MME 103 manages a tracking area list when the mobile terminal is in a standby state and an active state. The S-GW 104 transmits / receives user data to / from one or a plurality of base stations 102. The S-GW 104 becomes a local mobility anchor point at the time of handover between base stations. Further, there is a P-GW (PDN Gateway), which performs packet filtering and UE-ID address allocation for each user.

  Non-Patent Document 1 (Chapter 5) describes the current decisions regarding the frame configuration in the LTE system in 3GPP. This will be described with reference to FIG. FIG. 2 is an explanatory diagram showing a configuration of a radio frame used in the LTE communication system. In FIG. 2, one radio frame is 10 ms. The radio frame is divided into 10 equally sized sub-frames. The subframe is divided into two equally sized slots. A downlink synchronization signal (SS) is included in the first and sixth subframes for each radio frame. There are a first synchronization signal (Primary Synchronization Signal: P-SS) and a second synchronization signal (Secondary Synchronization Signal: S-SS). Channels other than MBSFN (Multimedia Broadcast multicast service Single Frequency Network) and channels other than MBSFN are multiplexed on a subframe basis. Hereinafter, a subframe for MBSFN transmission is referred to as an MBSFN sub-frame. Non-Patent Document 2 describes a signaling example at the time of MBSFN subframe allocation. FIG. 3 is an explanatory diagram showing the configuration of the MBSFN frame. In FIG. 3, an MBSFN subframe is allocated for each MBSFN frame (MBSFN frame). A set of MBSFN frames (MBSFN frame Cluster) is scheduled. A repetition period (Repetition Period) of a set of MBSFN frames is assigned.

  Non-Patent Document 1 describes the current decisions regarding the channel configuration in the LTE system in 3GPP. It is assumed that the same channel configuration as that of the non-CSG cell is used also in a CSG (Closed Subscriber Group cell) cell. A physical channel (Chapter 5 of Non-Patent Document 1) will be described with reference to FIG. FIG. 4 is an explanatory diagram illustrating physical channels used in the LTE communication system. In FIG. 4, a physical broadcast channel 401 (Physical Broadcast channel: PBCH) is a downlink channel transmitted from the base station 102 to the mobile terminal 101. A BCH transport block is mapped to four subframes in a 40 ms interval. There is no obvious signaling of 40ms timing. A physical control format indicator channel 402 (Physical Control format indicator channel: PCFICH) is transmitted from the base station 102 to the mobile terminal 101. PCFICH notifies base station 102 to mobile terminal 101 about the number of OFDM symbols used for PDCCHs. PCFICH is transmitted for each subframe. A physical downlink control channel 403 (Physical downlink control channel: PDCCH) is a downlink channel transmitted from the base station 102 to the mobile terminal 101. The PDCCH includes resource allocation, HARQ information related to DL-SCH (a downlink shared channel that is one of the transport channels shown in FIG. 5), and PCH (paging that is one of the transport channels shown in FIG. 5). Channel). The PDCCH carries an Uplink Scheduling Grant. The PDCCH carries ACK / Nack that is a response signal for uplink transmission. PDCCH is also called an L1 / L2 control signal. A physical downlink shared channel 404 (PDSCH) is a downlink channel transmitted from the base station 102 to the mobile terminal 101. PDSCH is mapped with DL-SCH (downlink shared channel) which is a transport channel and PCH which is a transport channel. A physical multicast channel 405 (Physical multicast channel: PMCH) is a downlink channel transmitted from the base station 102 to the mobile terminal 101. PMCH is mapped with MCH (multicast channel) which is a transport channel.

  A physical uplink control channel 406 (Physical Uplink control channel: PUCCH) is an uplink channel transmitted from the mobile terminal 101 to the base station 102. The PUCCH carries ACK / Nack which is a response signal (response) to downlink transmission. PUCCH carries a CQI (Channel Quality Indicator) report. CQI is quality information indicating the quality of received data or channel quality. The PUCCH carries a scheduling request (SR). A physical uplink shared channel 407 (Physical Uplink shared channel: PUSCH) is an uplink channel transmitted from the mobile terminal 101 to the base station 102. PUSCH is mapped with UL-SCH (uplink shared channel which is one of the transport channels shown in FIG. 5). A physical HARQ indicator channel 408 (Physical Hybrid ARQ indicator channel: PHICH) is a downlink channel transmitted from the base station 102 to the mobile terminal 101. The PHICH carries ACK / Nack that is a response to uplink transmission. A physical random access channel 409 (Physical random access channel: PRACH) is an uplink channel transmitted from the mobile terminal 101 to the base station 102. The PRACH carries a random access preamble.

  As the downlink reference signal, a symbol known as a mobile communication system is inserted into the first, third and last OFDM symbols of each slot. As a measurement of the physical layer of the mobile terminal, there is a reference symbol received power (RSRP).

  A transport channel (Chapter 5 of Non-Patent Document 1) will be described with reference to FIG. FIG. 5 is an explanatory diagram for explaining a transport channel used in an LTE communication system. FIG. 5A shows mapping between the downlink transport channel and the downlink physical channel. FIG. 5B shows mapping between the uplink transport channel and the uplink physical channel. For the downlink transport channel, a broadcast channel (BCH) is broadcast to the entire base station (cell). BCH is mapped to the physical broadcast channel (PBCH). Retransmission control by HARQ (Hybrid ARQ) is applied to the downlink shared channel (DL-SCH). Broadcasting to the entire base station (cell) is possible. Supports dynamic or semi-static resource allocation. Quasi-static resource allocation is also called Persistent Scheduling. In order to reduce power consumption of the mobile terminal, DRX (Discontinuous reception) of the mobile terminal is supported. DL-SCH is mapped to a physical downlink shared channel (PDSCH). A paging channel (Paging channel: PCH) supports DRX of the mobile terminal in order to enable low power consumption of the mobile terminal. Notification to the entire base station (cell) is required. It is mapped to a physical resource such as a physical downlink shared channel (PDSCH) that can be dynamically used for traffic, or a physical resource such as a physical downlink control channel (PDCCH) of another control channel. A multicast channel (Multicast channel: MCH) is used for broadcast to the entire base station (cell). Supports SFN combining of MBMS services (MTCH and MCCH) in multi-cell transmission. Supports quasi-static resource allocation. MCH is mapped to PMCH.

  Retransmission control by HARQ (Hybrid ARQ) is applied to the uplink shared channel (UL-SCH). Supports dynamic or semi-static resource allocation. UL-SCH is mapped to a physical uplink shared channel (PUSCH). The random access channel (Random access channel: RACH) shown in FIG. 5B is limited to control information. There is a risk of collision. The RACH is mapped to a physical random access channel (PRACH). HARQ will be described.

  HARQ is a technique for improving the communication quality of a transmission path by combining automatic repeat request and error correction (forward error correction). There is also an advantage that error correction functions effectively by retransmission even for a transmission path in which communication quality changes. In particular, further quality improvement can be obtained by combining the reception result of the initial transmission and the reception result of the retransmission upon retransmission. An example of the retransmission method will be described. When the reception data cannot be decoded correctly on the receiving side (when a CRC Cyclic Redundancy Check error occurs (CRC = NG)), “Nack” is transmitted from the receiving side to the transmitting side. The transmission side that has received “Nack” retransmits the data. When the reception data can be correctly decoded on the reception side (when no CRC error occurs (CRC = OK)), “Ack” is transmitted from the reception side to the transmission side. The transmitting side that has received “Ack” transmits the next data. An example of the HARQ method is “Chase Combining”. Chase combining is a method in which the same data sequence is transmitted for initial transmission and retransmission, and the gain is improved by combining the initial transmission data sequence and the retransmission data sequence in retransmission. The idea is that even if there is an error in the initial transmission data, it is partially accurate, and it is possible to transmit data with higher accuracy by combining the initial transmission data and the retransmission data of the correct part. Based on. Another example of the HARQ scheme is IR (Incremental Redundancy). IR is to increase the redundancy. By transmitting parity bits in retransmission, the redundancy is increased in combination with the initial transmission, and the quality is improved by the error correction function.

  The logical channel (Chapter 6 of Non-Patent Document 1) will be described with reference to FIG. FIG. 6 is an explanatory diagram illustrating logical channels used in the LTE communication system. FIG. 6A shows mapping between the downlink logical channel and the downlink transport channel. FIG. 6B shows mapping between the uplink logical channel and the uplink transport channel. A broadcast control channel (BCCH) is a downlink channel for broadcast system control information. The BCCH that is a logical channel is mapped to a broadcast channel (BCH) that is a transport channel or a downlink shared channel (DL-SCH). A paging control channel (Paging control channel: PCCH) is a downlink channel for transmitting a paging signal. PCCH is used when the network does not know the cell location of the mobile terminal. The PCCH that is a logical channel is mapped to a paging channel (PCH) that is a transport channel. The common control channel (CCCH) is a channel for transmission control information between the mobile terminal and the base station. CCCH is used when the mobile terminal does not have an RRC connection with the network. In the downlink method, CCCH is mapped to a downlink shared channel (DL-SCH) that is a transport channel. In the uplink direction, the CCCH is mapped to an uplink shared channel (UL-SCH) that is a transport channel.

  A multicast control channel (MCCH) is a downlink channel for one-to-many transmission. This is a channel used for transmission of MBMS control information for one or several MTCHs from the network to the mobile terminal. MCCH is a channel used only for a mobile terminal receiving MBMS. MCCH is mapped to a downlink shared channel (DL-SCH) or multicast channel (MCH) which is a transport channel. The dedicated control channel (Dedicated control channel: DCCH) is a channel for transmitting dedicated control information between the mobile terminal and the network. The DCCH is mapped to the uplink shared channel (UL-SCH) in the uplink, and is mapped to the downlink shared channel (DL-SCH) in the downlink. The dedicated traffic channel (Dedicate Traffic channel: DTCH) is a channel for one-to-one communication to individual mobile terminals for transmission of user information. DTCH exists for both uplink and downlink. The DTCH is mapped to the uplink shared channel (UL-SCH) in the uplink, and is mapped to the downlink shared channel (DL-SCH) in the downlink. A multicast traffic channel (Multicast Traffic channel: MTCH) is a downlink channel for transmitting traffic data from a network to a mobile terminal. MTCH is a channel used only for a mobile terminal that is receiving MBMS. The MTCH is mapped to the downlink shared channel (DL-SCH) or multicast channel (MCH).

  GCI is a global cell identity. A CSG cell (Closed Subscriber Group cell) is introduced in LTE and UMTS (Universal Mobile Telecommunication System). CSG will be described below (Chapter 3.1 of Non-Patent Document 4). A CSG (Closed Subscriber Group) is a cell in which an operator identifies an available subscriber (a cell for a specific subscriber). The identified subscriber is allowed to access one or more E-UTRAN cells of the Public Land Mobile Network (PLMN). One or more E-UTRAN cells to which the identified subscribers are allowed access are referred to as “CSG cell (s)”. However, PLMN has access restrictions. A CSG cell is a part of a PLMN that broadcasts a unique CSG identity (CSG identity: CSG ID, CSG-ID). Members of the subscriber group who have been registered for use in advance and access the CSG cell using the CSG-ID that is the access permission information. The CSG-ID is broadcast by the CSG cell or the cell. There are a plurality of CSG-IDs in a mobile communication system. The CSG-ID is then used by the mobile terminal (UE) to facilitate access of CSG related members. It has been discussed at the 3GPP meeting that a CSG cell or information broadcast by the cell is made a tracking area code (TAC) instead of a CSG-ID. The location tracking of a mobile terminal is performed in units of areas composed of one or more cells. The position tracking is to enable tracking of the position of the mobile terminal and calling (the mobile terminal receives a call) even in the standby state. This area for tracking the location of the mobile terminal is called a tracking area. The CSG white list is a list stored in the USIM in which all CSG IDs of the CSG cells to which the subscriber belongs are recorded. The white list in the mobile terminal is given by the upper layer. Thereby, the base station of the CSG cell allocates radio resources to the mobile terminal.

  A “suitable cell” will be described below (Chapter 4.3 of Non-Patent Document 4). A “suitable cell” is a cell in which the UE camps on to receive normal service. Such a cell was provided by (1) the non-access stratum (2) the (1) the cell is the selected or registered PLMN, or part of the PLMN in the “Equivalent PLMN list” The latest information must satisfy the following conditions: (a) The cell is not a barred cell. (b) The cell is not part of the “banned LAs for roaming” list, but part of at least one tracking area (TA). In that case, the cell needs to satisfy the above (1), (c) the cell satisfies the cell selection evaluation criteria, and (d) the cell is a CSG cell as system information (System Information: SI). ), The CSG-ID is part of the UE's “CSG WhiteList” (included in the UE's CSG WhiteList).

  An “acceptable cell” will be described below (Chapter 4.3 of Non-Patent Document 4). This is a cell where a UE camps on in order to receive a limited service (emergency call). Such a cell shall meet all the following requirements: That is, the minimum set of requirements for initiating an emergency call in an E-UTRAN network is shown below. (1) The cell is not a barred cell. (2) The cell satisfies the cell selection evaluation criteria.

  In 3GPP, base stations called Home-NodeB (Home-NB, HNB) and Home-eNodeB (Home-eNB, HeNB) are being studied. HNB / HeNB is a base station for UTRAN / E-UTRAN, for example, for home, corporate, and commercial access services. Non-Patent Document 6 discloses three different modes of access to HeNB and HNB. An open access mode, a closed access mode, and a hybrid access mode. Each mode has the following characteristics. In the open access mode, the HeNB or HNB is operated as a normal cell of a normal operator. In the closed access mode, the HeNB or HNB is operated as a CSG cell. This is a CSG cell accessible only to CSG members. In the hybrid access mode, a non-CSG member is a CSG cell to which access is permitted at the same time. In other words, the cell in the hybrid access mode is a cell that supports both the open access mode and the closed access mode.

3GPP TS36.300 V8.6.0 Chapter 4, Chapter 5, Chapter 6

3GPP R1-072963

TR R3.020V0.6.0

3GPP TS36.304 V8.4.0 3.1, 4.3, 5.2.4.2, 5.2.4.3, 5.2.4.6

3GPP R2-082899

3GPP S1-083461

3GPP R2-075149

3GPP TS36.331 V8.4.0 chapter 5.2, chapter 5.5, chapter 6.3.1

3GPP TR25.820 V8.2.0 5.1.1

  The HeNB and HNB are required to support various services. For example, an operator increases the radio resources that the mobile terminal can use by allowing the mobile terminal to be registered in a certain HeNB and HNB and allowing only the registered mobile terminal to access the HeNB and HNB cells. To enable high-speed communication. Accordingly, the operator sets the charging fee higher than usual. Service. In order to realize such services, a CSG (Closed Subscriber Group cell) cell that can be accessed only by registered (subscribed, member) mobile terminals has been introduced. Many CSG (Closed Subscriber Group cell) cells are required to be installed in shopping streets, condominiums, schools, companies, and the like. For example, a CSG cell is installed for each store in a shopping street, each room in an apartment, each classroom in a school, and each section in a company, and only a user registered in each CSG cell can use the CSG cell. Is required. HeNB / HNB is required not only to complement communication outside the coverage of the macro cell but also to support various services as described above. For this reason, the case where many HeNB / HNBs are installed also arises. In addition, the cell radius of HeNB / HNB is expected to be smaller than the cell radius of the macro cell.

  When many HeNBs / HNBs are installed, since the cell radius is small, the number of times of cell reselection between the HeNB / HNB is increased in the mobile terminal compared to the case where only the macro cell is arranged. An increase in cell reselection requires a larger number of times the mobile terminal receives broadcast information of a new cell by an increase in cell reselection, which causes a problem of increased power consumption of the mobile terminal.

  The mobile communication system according to the present invention transmits and receives data using an OFDM (Orthogonal Frequency Division Multiplexing) scheme as a downlink access scheme and an SC-FDMA (Single Career Frequency Division Multiple Access) scheme as an uplink access scheme. A first cell forming an area communicable with a mobile terminal and a mobile terminal located in a predetermined area, a second cell forming an area communicable with the mobile terminal within a range narrower than the first cell In a mobile communication system including a base station provided in each cell, a mobile terminal determines movement state information indicating a movement state of the mobile terminal based on the number of times of cell selection performed for a certain period of time. In addition, cell selection is performed based on the movement state information and a parameter for controlling cell selection notified from the base station. When the cell is the first cell, a count is added to the number of times of cell selection for detecting the moving state, and when the selected cell is the second cell, the number of times of selecting the cell for detecting the moving state is counted. Is not added.

  The mobile communication system according to the present invention transmits and receives data using an OFDM (Orthogonal Frequency Division Multiplexing) scheme as a downlink access scheme and an SC-FDMA (Single Career Frequency Division Multiple Access) scheme as an uplink access scheme. A first cell forming an area communicable with a mobile terminal and a mobile terminal located in a predetermined area, a second cell forming an area communicable with the mobile terminal within a range narrower than the first cell In a mobile communication system including a base station provided in each cell, a mobile terminal determines movement state information indicating a movement state of the mobile terminal based on the number of times of cell selection performed for a certain period of time. In addition, cell selection is performed based on the movement state information and a parameter for controlling cell selection notified from the base station. When the information is in a high-speed movement state, cell selection or handover to the first cell is performed, cell selection and handover to the second cell are not performed, and movement state information is in the medium-speed movement state or the normal movement state. At some time, cell selection and handover to the first cell or the second cell are performed.

  The mobile communication system according to the present invention transmits and receives data using an OFDM (Orthogonal Frequency Division Multiplexing) scheme as a downlink access scheme and an SC-FDMA (Single Career Frequency Division Multiple Access) scheme as an uplink access scheme. A first cell forming an area communicable with a mobile terminal and a mobile terminal located in a predetermined area, a second cell forming an area communicable with the mobile terminal within a range narrower than the first cell In a mobile communication system including a base station provided in each cell, a mobile terminal determines movement state information indicating a movement state of the mobile terminal based on the number of times of cell selection performed for a certain period of time. In addition, the cell selection is performed based on the movement state information and the parameter for controlling the cell selection notified from the base station. Counts the number of cell selections performed in step 1, and controls cell selection or handover when the number of consecutive selections exceeds a predetermined threshold, or when the number of cell selections for the same cell exceeds a predetermined threshold within a specified time. To do.

  The mobile communication system according to the present invention transmits and receives data using an OFDM (Orthogonal Frequency Division Multiplexing) scheme as a downlink access scheme and an SC-FDMA (Single Career Frequency Division Multiple Access) scheme as an uplink access scheme. A first cell forming an area communicable with a mobile terminal and a mobile terminal located in a predetermined area, a second cell forming an area communicable with the mobile terminal within a range narrower than the first cell In a mobile communication system including a base station provided in each cell, a mobile terminal determines movement state information indicating a movement state of the mobile terminal based on the number of times of cell selection performed for a certain period of time. In addition, cell selection is performed based on the movement state information and a parameter for controlling cell selection notified from the base station. When the cell is the first cell, a count is added to the cell selection count, and when the selected cell is the second cell, the count is not added to the cell selection count for moving state detection. The selection of the second cell does not affect the determination of the movement state of the mobile terminal. Therefore, it is possible to appropriately adjust parameters for controlling cell selection, and it is possible to prevent an increase in cell reselection. Preventing an increase in cell reselection leads to a reduction in the number of times a mobile terminal receives broadcast information of a new cell. Therefore, the effect of reducing power consumption of the mobile terminal can be obtained.

  The mobile communication system according to the present invention transmits and receives data using an OFDM (Orthogonal Frequency Division Multiplexing) scheme as a downlink access scheme and an SC-FDMA (Single Career Frequency Division Multiple Access) scheme as an uplink access scheme. A first cell forming an area communicable with a mobile terminal and a mobile terminal located in a predetermined area, a second cell forming an area communicable with the mobile terminal within a range narrower than the first cell In a mobile communication system including a base station provided in each cell, a mobile terminal determines movement state information indicating a movement state of the mobile terminal based on the number of times of cell selection performed for a certain period of time. In addition, cell selection is performed based on the movement state information and a parameter for controlling cell selection notified from the base station. When the information is in a high-speed movement state, cell selection or handover to the first cell is performed, cell selection and handover to the second cell are not performed, and movement state information is in the medium-speed movement state or the normal movement state. Since cell selection or handover to the first cell and the second cell is performed at a certain time, it becomes possible to prevent repeated cell reselection, and an effect of reducing power consumption of the mobile terminal can be obtained. In addition, it is possible to prevent repeated handovers, and it is possible to obtain effects such as effective utilization of radio resources, reduction of control delay as a mobile communication system, and reduction of power consumption of a mobile terminal.

  The mobile communication system according to the present invention transmits and receives data using an OFDM (Orthogonal Frequency Division Multiplexing) scheme as a downlink access scheme and an SC-FDMA (Single Career Frequency Division Multiple Access) scheme as an uplink access scheme. A first cell forming an area communicable with a mobile terminal and a mobile terminal located in a predetermined area, a second cell forming an area communicable with the mobile terminal within a range narrower than the first cell In a mobile communication system including a base station provided in each cell, a mobile terminal determines movement state information indicating a movement state of the mobile terminal based on the number of times of cell selection performed for a certain period of time. In addition, the cell selection is performed based on the movement state information and the parameter for controlling the cell selection notified from the base station. The cell selection or handover is regulated when the number of consecutive cell selections exceeds the predetermined threshold, or when the number of cell selections for the same cell exceeds the predetermined threshold within a specified time. Therefore, when a ping-pong phenomenon in which reselection is repeated between the same cells is detected, a mobile communication system in which cell reselection and handover are difficult can be achieved. As a result, even if a mobile terminal located in the vicinity of the cell boundary moves minutely or changes in the wireless environment, cell reselection or handover can be prevented.

It is explanatory drawing which shows the structure of the communication system of a LTE system. It is explanatory drawing which shows the structure of the communication system of a LTE system. FIG. 2 is an explanatory diagram showing a configuration of a radio frame used in an LTE communication system. It is explanatory drawing which shows the structure of a MBSFN (Multimedia Broadcast multicast service Single Frequency Network) frame. It is explanatory drawing explaining the physical channel used with the communication system of a LTE system. It is explanatory drawing explaining the transport channel used with the communication system of a LTE system. It is explanatory drawing explaining the logical channel used with the communication system of a LTE system. It is a block diagram which shows the whole structure of the mobile communication system currently discussed by 3GPP. It is a block diagram which shows the structure of the mobile terminal 311 which concerns on this invention. It is a block diagram which shows the structure of the base station 312 which concerns on this invention. It is a block diagram which shows the structure of MME which concerns on this invention. It is a block diagram which shows the structure of HeNBGW which concerns on this invention. It is a flowchart which shows the outline of the cell search which a mobile terminal (UE) performs in the communication system of a LTE system. FIG. 3 is a conceptual diagram illustrating a problem of the first embodiment. FIG. 3 is a sequence diagram showing an operation of the mobile communication system in the first embodiment. 6 is a flowchart for determining whether or not to perform cell reselection performed by a mobile terminal in the first embodiment. FIG. 11 is a sequence diagram showing an operation of the mobile communication system in the first modification of the first embodiment. FIG. 11 is a sequence diagram showing an operation of the mobile communication system in the second modification of the first embodiment. FIG. 11 is a sequence diagram showing an operation of a mobile communication system in a third modification of the first embodiment. 6 is a flowchart showing an operation of a mobile terminal in the second embodiment. FIG. 10 is a conceptual diagram showing the effect of the second embodiment. 10 is a flowchart showing an operation of a mobile terminal in Modification 1 of Embodiment 2. 10 is a flowchart showing an operation of a mobile terminal in a second modification of the second embodiment. 10 is a flowchart showing an operation of a mobile terminal in a third modification of the second embodiment. 10 is a flowchart showing an operation of a mobile terminal in a fourth modification of the second embodiment. FIG. 10 is a sequence diagram showing an operation of a mobile communication system in a fifth modification of the second embodiment. FIG. 10 is a conceptual diagram illustrating a problem in a third embodiment. FIG. 11 is a sequence diagram showing an operation of the mobile communication system in the third embodiment. FIG. 10 is a conceptual diagram showing the effect of the third embodiment. FIG. 10 is a conceptual diagram showing a problem of Modification 1 of Embodiment 3. FIG. 11 is a sequence diagram showing an operation of a mobile communication system in a first modification of the third embodiment. FIG. 11 is a sequence diagram showing an operation of a mobile communication system in a second modification of the third embodiment.

Embodiment 1 FIG.
FIG. 7 is a block diagram showing the overall configuration of an LTE mobile communication system currently under discussion in 3GPP. Currently, in 3GPP, CSG (Closed Subscriber Group) cells (e-UTRAN Home-eNodeB (Home-eNB, HeNB), UTRAN Home-NB (HNB)) and non-CSG cells (e-UTRAN eNodeB (eNB) ), UTRAN NodeB (NB), GERAN BSS) and other systems are being studied. For e-UTRAN, configurations such as (a) and (b) in FIG. It has been proposed (Non-Patent Document 1, Non-Patent Document 3). FIG. 7A will be described. A mobile terminal (UE) 71 performs transmission / reception with the base station 72. The base station 72 is classified into an eNB (non-CSG cell) 72-1 and a Home-eNB (CSG cell) 72-2. The eNB 72-1 is connected to the MME 73 via the interface S1, and control information is communicated between the eNB and the MME. A plurality of MMEs are connected to one eNB. The Home-eNB 72-2 is connected to the MME 73 via the interface S1, and control information is communicated between the Home-eNB and the MME. A plurality of Home-eNBs are connected to one MME.

  Next, FIG. 7B will be described. A mobile terminal (UE) 71 performs transmission / reception with the base station 72. The base station 72 is classified into an eNB (non-CSG cell) 72-1 and a Home-eNB (CSG cell) 72-2. As in FIG. 7A, the eNB 72-1 is connected to the MME 73 via the interface S1, and control information is communicated between the eNB and the MME. A plurality of MMEs are connected to one eNB. On the other hand, Home-eNB 72-2 is connected to MME 73 via HeNBGW (Home-eNB GateWay) 74. Home-eNB and HeGW are connected by interface S1, and HeNBGW74 and MME73 are connected via interface S1_flex. One or a plurality of Home-eNBs 72-2 are connected to one HeNBGW 74, and information is communicated through S1. The HeNBGW 74 is connected to one or a plurality of MMEs 73, and information is communicated through S1_flex.

  By connecting one HeNBGW 74 to a Home-eNB belonging to the same CSG-ID using the configuration of FIG. 7B, a plurality of information belonging to the same CSG-ID, such as registration information, can be obtained from the MME 73. When transmitting to the Home-eNB 72-2, it is once transmitted to the HeNBGW 74, and then transmitted to the plurality of Home-eNBs 7-2, thereby signaling efficiency than directly transmitting to each of the plurality of Home-eNBs 72-2. Can be enhanced. On the other hand, when each Home-eNB 72-2 communicates individual information with the MME 73, the Home-eNB 72-2 is only passed (transmitted) through the HeNBGW 74 without processing the information there. And MME 73 can communicate with each other as if they were directly connected.

  FIG. 8 is a block diagram showing a configuration of a mobile terminal (terminal 71 in FIG. 7) according to the present invention. Transmission processing of the mobile terminal shown in FIG. 8 will be described. First, control data from the protocol processing unit 801 and user data from the application unit 802 are stored in the transmission data buffer unit 803. The data stored in the transmission data buffer unit 803 is transferred to the encoder unit 804 and subjected to encoding processing such as error correction. There may exist data that is directly output from the transmission data buffer unit 803 to the modulation unit 805 without being encoded. The data encoded by the encoder unit 804 is subjected to modulation processing by the modulation unit 805. The modulated data is converted into a baseband signal, and then output to the frequency conversion unit 806 where it is converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted from the antenna 807 to the base station 312. In addition, the reception process of the mobile terminal 311 is executed as follows. A radio signal from the base station 312 is received by the antenna 807. The reception signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 806, and demodulated by the demodulation unit 808. The demodulated data is transferred to the decoder unit 809 and subjected to decoding processing such as error correction. Of the decoded data, control data is passed to the protocol processing unit 801, and user data is passed to the application unit 802. A series of processing of the mobile terminal is controlled by the control unit 810. Therefore, the control unit 810 is connected to each unit (801 to 809), which is omitted in the drawing.

  FIG. 9 is a block diagram showing the configuration of the base station (base station 72 of FIG. 7) according to the present invention. A transmission process of the base station shown in FIG. 9 will be described. The EPC communication unit 901 transmits and receives data between the base station 72 and EPC (MME73, HeNBGW74, etc.). The other base station communication unit 902 transmits / receives data to / from other base stations. The EPC communication unit 901 and the other base station communication unit 902 exchange information with the protocol processing unit 903, respectively. Control data from the protocol processing unit 903 and user data and control data from the EPC communication unit 901 and the other base station communication unit 902 are stored in the transmission data buffer unit 904. Data stored in the transmission data buffer unit 904 is transferred to the encoder unit 905 and subjected to encoding processing such as error correction. There may exist data that is directly output from the transmission data buffer unit 904 to the modulation unit 906 without being encoded. The encoded data is subjected to modulation processing by the modulation unit 906. The modulated data is converted into a baseband signal, and then output to the frequency conversion unit 907 to be converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted from the antenna 908 to one or a plurality of mobile terminals 71. Further, the reception process of the base station 72 is executed as follows. Radio signals from one or a plurality of mobile terminals 311 are received by the antenna 908. The received signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 907, and demodulated by the demodulation unit 909. The demodulated data is transferred to the decoder unit 910, and decoding processing such as error correction is performed. Of the decoded data, the control data is passed to the protocol processing unit 903 or the EPC communication unit 901 and the other base station communication unit 902, and the user data is passed to the EPC communication unit 901 and the other base station communication unit 902. A series of processing of the base station 72 is controlled by the control unit 911. Therefore, although the control part 911 is abbreviate | omitted in drawing, it is connected with each part (901-910).

  FIG. 10 is a block diagram showing a configuration of an MME (Mobility Management Entity) according to the present invention. The PDN GW communication unit 1001 transmits and receives data between the MME 73 and the PDN GW. The base station communication unit 1002 transmits and receives data between the MME 73 and the base station 72 using the S1 interface. When the data received from the PDN GW is user data, the user data is passed from the PDN GW communication unit 1001 to the base station communication unit 1002 via the user plane processing unit 1003 and transmitted to one or a plurality of base stations 72. The When the data received from the base station 72 is user data, the user data is transferred from the base station communication unit 1002 to the PDN GW communication unit 1001 via the user plane processing unit 1003 and transmitted to the PDN GW.

  When the data received from the PDN GW is control data, the control data is transferred from the PDN GW communication unit 1001 to the control plane control unit 1005. When the data received from the base station 72 is control data, the control data is transferred from the base station communication unit 1002 to the control plane control unit 1005. The HeNBGW communication unit 1004 is provided when the HeNBGW 74 exists, and performs data transmission / reception through an interface (IF) between the MME 73 and the HeNBGW 74 depending on the information type. The control data received from the HeNBGW communication unit 1004 is passed from the HeNBGW communication unit 1004 to the control plane control unit 1005. The result of the process in the control plane control unit 1005 is transmitted to the PDN GW via the PDN GW communication unit 1001. Further, the result processed by the control plane control unit 1005 is transmitted to one or a plurality of base stations 72 via the S1 interface via the base station communication unit 1002, and to one or a plurality of HeNBGWs 74 via the HeNBGW communication unit 1004. Sent.

  The control plane control unit 1005 includes a NAS security unit 1005-1, an SAE bearer control unit 1005-2, an idle state mobility management unit 1005-3, and the like, and performs overall processing for the control plane. The NAS security unit 1005-1 performs security of a NAS (Non-Access Stratum) message. The SAE bearer control unit 1005-2 manages the SAE (System Architecture Evolution) bearer. The idle state mobility management unit 1005-3 performs mobility management in a standby state (LTE-IDLE state, also simply referred to as idle), generation and control of a paging signal in the standby state, and one or more mobile terminals 71 being served thereby Tracking area (TA) addition, deletion, update, search, tracking area list (TA List) management and so on. The MME initiates the paging protocol by transmitting a paging message to a cell belonging to a tracking area (tracking area: TA) in which the UE is registered. The idle state mobility management unit 1005-3 may perform CSG management, CSG-ID management, and white list management of the Home-eNB 72-2 connected to the MME. In the management of CSG-ID, the relationship between the mobile terminal corresponding to the CSG-ID and the CSG cell is managed (added, deleted, updated, searched). For example, it may be a relationship between one or a plurality of mobile terminals registered for user access with a certain CSG-ID and a CSG cell belonging to the CSG-ID. In white list management, the relationship between a mobile terminal and a CSG-ID is managed (added, deleted, updated, searched). For example, the white list may store one or a plurality of CSG-IDs registered by a certain mobile terminal as a user. These CSG-related management may be performed in other parts of the MME 73, but by performing in the idle state mobility management unit 1005-3, tracking is performed instead of the CSG-ID currently being discussed at the 3GPP meeting. A method using an area code (Tracking Area Code) can be performed efficiently. A series of processing of the MME 313 is controlled by the control unit 1006. Therefore, although the control part 1006 is abbreviate | omitted in drawing, it is connected with each part (1001-1005).

  FIG. 11 is a block diagram showing the configuration of the HeNBGW according to the present invention. The EPC communication unit 1101 transmits and receives data between the HeNBGW 74 and the MME 73 using the S1_flex interface. The base station communication unit 1102 transmits and receives data between the HeNBGW 74 and the Home-eNB 72-2 using the S1 interface. The location processing unit 1103 performs a process of transmitting registration information and the like to a plurality of Home-eNBs among data from the MME 73 passed via the EPC communication unit 1101. The data processed by the location processing unit 1103 is transferred to the base station communication unit 1102 and transmitted to one or more Home-eNBs 72-2 via the S1 interface. Data that does not require processing in the location processing unit 1103 and is simply passed (transmitted) is passed from the EPC communication unit 1101 to the base station communication unit 1102 and is sent to one or a plurality of Home-eNBs 72-2 via the S1 interface. Sent. A series of processing of the HeNBGW 74 is controlled by the control unit 1104. Therefore, the control unit 1104 is connected to each unit (1101 to 1103), which is omitted in the drawing.

  Next, an example of a general cell search method in a mobile communication system will be shown. FIG. 12 is a flowchart illustrating an outline from a cell search to a standby operation performed by a mobile terminal (UE) in an LTE communication system. When cell search is started in the mobile terminal, slot timing and frame timing using the first synchronization signal (P-SS) and second synchronization signal (S-SS) transmitted from the neighboring base stations in step ST1201. Synchronize. In combination with P-SS and S-SS, the synchronization signal (SS) is assigned a synchronization code corresponding to a PCI (Physical Cell Identity) assigned to each cell. Currently, 504 PCIs are being studied, and the 504 PCIs are used for synchronization, and the PCI of the synchronized cell is detected (specified). Next, for a synchronized cell, in step ST1202, a reference signal RS (Reference Signal) transmitted from the base station for each cell is detected, and the received power is measured. The reference signal RS uses a code corresponding to PCI one-to-one, and can be separated from other cells by correlating with the code. By deriving the RS code of the cell from the PCI specified in ST1201, it becomes possible to detect the RS and measure the RS received power. Next, in ST1203, a cell having the best RS reception quality (for example, a cell having the highest RS reception power, that is, the best cell) is selected from one or more cells detected up to ST1202. Next, in ST 1204, PBCH of the best cell is received, and BCCH which is broadcast information is obtained. A MIB (Master Information Block) including cell configuration information is carried on the BCCH on the PBCH. MIB information includes, for example, DL (downlink) system bandwidth, the number of transmission antennas, SFN (System Frame Number), and the like.

  Next, at 1205, the DL-SCH of the cell is received based on the MIB cell configuration information, and SIB (System Information Block) 1 in the broadcast information BCCH is obtained. SIB1 includes information about access to the cell, information about cell selection, and scheduling information of other SIBs (SIBk; integer of k ≧ 2). SIB1 includes a TAC (Tracking Area Code). Next, in ST1206, the mobile terminal compares the TAC received in ST1205 with the TAC already held by the mobile terminal. If the result of the comparison is the same, a standby operation is started in the cell. If they are different from each other, the mobile terminal requests a change of TA in order to perform TAU (Tracking Area Update) to the core network (Core Network, EPC) (including MME) through the cell. The core network updates the TA based on the identification number (UE-ID or the like) of the mobile terminal sent from the mobile terminal together with the TAU request signal. After updating the TA, the core network transmits a TAU acceptance signal to the mobile terminal. The mobile terminal rewrites (updates) the TAC (or TAC list) held by the mobile terminal with the TAC of the cell. Thereafter, the mobile terminal enters a standby operation in the cell.

  In LTE and UMTS (Universal Mobile Telecommunication System), introduction of a CSG (Closed Subscriber Group) cell is being studied. As described above, access is permitted only to one or a plurality of mobile terminals registered in the CSG cell. One or a plurality of mobile terminals registered with the CSG cell constitute one CSG. A unique identification number called CSG-ID is assigned to the CSG configured as described above. A single CSG may have a plurality of CSG cells. If a mobile terminal registers in one of the CSG cells, it can access other CSG cells to which the CSG cell belongs. In addition, Home-eNB in LTE and Home-NB in UMTS may be used as a CSG cell. The mobile terminal registered in the CSG cell has a white list. Specifically, the white list is stored in the SIM / USIM. The white list carries CSG information of the CSG cell registered by the mobile terminal. Specifically, CSG-ID, TAI (Tracking Area Identity), TAC, etc. can be considered as CSG information. If CSG-ID and TAC are associated with each other, either one is sufficient. Further, GCI may be used as long as CSG-ID or TAC is associated with GCI (Global Cell Identity). From the above, a mobile terminal that does not have a white list (including the case where the white list is empty in the present invention) cannot access a CSG cell, and only accesses a non-CSG cell. Can not. On the other hand, a mobile terminal having a white list can access both a registered CSG-ID CSG cell and a non-CSG cell.

  In 3GPP, it is discussed to divide all PCIs (Physical Cell Identity) into CSG cells and non-CSG cells (referred to as PCI split) (Non-Patent Document 5). Further, it is discussed that the PCI split information is reported from the base station to the mobile terminals being served by the system information. A basic operation of a mobile terminal using PCI split is disclosed. A mobile terminal that does not have PCI split information needs to perform a cell search using all PCIs (for example, using all 504 codes). On the other hand, a mobile terminal having PCI split information can perform a cell search using the PCI split information.

  In 3GPP, a cell reselection method of a mobile terminal is disclosed (Non-patent Documents 4 Chapters 5.2.4.2 and 5.2.4.6). Measurement for cell reselection is performed under the following conditions. When the parameter (S_intrasearch) is notified from the serving cell and the reception level value of the serving cell is larger than the parameter, the measurement is not performed. On the other hand, when the parameter is not notified from the serving cell, or when the reception level value of the serving cell is equal to or less than the parameter, measurement is performed. A serving cell refers to a base station that performs scheduling of radio resources for a mobile terminal. 3GPP discloses cell reselection criteria. Cell ranking (referred to as cell-ranking) is performed as follows. The serving cell and the neighboring cell (s) are ranked using the value obtained by adding the adjustment parameter (Q_Hyst) to the measurement value of the serving cell and the value obtained by subtracting the adjustment parameter (Q_offset) from the measurement value of the neighboring cell. When the following two conditions are satisfied, the mobile terminal performs reselection to a new cell. (1) A new cell is ranked better (or higher) than the serving cell for a certain period (T_reselection). (2) One second or more has passed since the current serving cell was camped on.

  3GPP discloses the movement state of mobile terminals (referred to as mobility states) (Non-Patent Document 4 Chapter 5.2.4.3). From the serving cell, T_CRmax, N_CR_H, N_CR_M, T_CRmaxHyst, etc. are reported as system information as mobility state parameters. The medium-mobility state criterion is that the number of cell reselections for detecting the movement state exceeds the medium speed threshold (N_CR_M) during a certain period (T_CRmax), and the high speed threshold (N_CR_H) Is not exceeded. When the mobile terminal detects the medium speed movement state, the mobile terminal transitions to the medium speed movement state. The criterion for the high-mobility state is a case where the number of reselection of the cell for detecting the movement state exceeds the high-speed threshold (N_CR_H) in a certain period (T_CRmax). When the mobile terminal detects the high-speed movement state, the mobile terminal transitions to the high-speed movement state. The mobile terminal does not count reselection between the same two cells for detecting the moving state. When the mobile terminal detects neither a medium speed movement state nor a high speed movement state in a certain period (T_CRmaxHyst), the mobile terminal transits to a normal movement state (Normal-mobility state).

  A scaling method according to the movement state is defined (Non-Patent Document 4 Chapter 5.2.4.3). The scaling method is not applied unless it is in a medium speed movement state or a high speed movement state. When the high speed movement state is detected, the measurement value adjustment parameter (Q_hyst) of the serving cell used for cell ranking is adjusted for the high speed movement state. Specifically, the measurement value adjustment parameter (Q_hyst) of the serving cell is multiplied by a scaling factor for a high-speed movement state for the measurement value adjustment parameter of the serving cell (Speed dependent scaling factor for Q_hyst for high Mobility state). When the medium speed movement state is detected, the measurement value adjustment parameter (Q_hyst) of the serving cell used for cell ranking is adjusted for the medium speed movement state. Specifically, the measurement value adjustment parameter (Q_hyst) of the serving cell is multiplied by a scaling factor for a medium speed movement state for the measurement value adjustment parameter of the serving cell (Speed dependent scaling factor for Q_hyst for medium Mobility state). The scaling factor for the high speed movement state for the measurement value adjustment parameter of the serving cell and the scaling factor for the medium speed movement state for the measurement value adjustment parameter of the serving cell are reported as system information from the serving cell.

  In 3GPP, a cell reselection method according to the movement state of the mobile terminal is discussed (Non-Patent Document 7). It is described that cell reselection is facilitated if the mobile terminal is in a high-speed movement state. Further, it is described that a “ping-pong phenomenon” in which cell reselection is repeated occurs at a cell boundary. It is described that when a mobile terminal determines a movement state by counting the number of cell reselections, it is determined that the mobile terminal is in a high-speed movement state if a ping-pong phenomenon occurs. It has been pointed out that the mobile terminal cannot recover from this situation because cell reselection is more easily adjusted in a fast moving state. Non-Patent Document 7 describes that the problem is solved by changing the moving state determination method of the mobile terminal to a method using Doppler frequency measurement.

  A problem to be solved in the first embodiment will be described. When a large number of HeNBs (which may be HNBs) are installed within the coverage of a macro cell, since the cell radius is small, cell re-transmission between HeNBs is performed in a mobile terminal compared to a case where only a macro cell is arranged. Increase the number of selections. This will be described with reference to FIG. FIG. 13A shows that the mobile terminal 1302 existing within the coverage of the macro cell 1301 moves as indicated by an arrow. FIG. 13B shows a case where the mobile terminal moves at the same moving speed at a location where many HeNBs are installed. In a location where many HeNBs are installed even at the same moving speed, the mobile terminal 1302 repeats cell reselection with the HeNB 1303, the HeNB 1304, the HeNB 1305, the HeNB 1306, and the HeNB 1307. In FIG. 13A, the number of reselections is 0, whereas in FIG. 13B, the number of reselections is 4. At this time, a case is considered in which the cell reselection count disclosed in Non-Patent Document 4 is used as a mobile terminal movement state determination method. Even if the actual moving speed of the mobile terminal is the same, cell reselection may occur repeatedly at a location where a large number of HeNBs are installed, compared to the case where only the macro cell is arranged. Therefore, in a location where many HeNBs are installed, the probability of being determined as a high-speed movement state or a medium-speed movement state increases.

  As shown in Non-Patent Document 7, let us consider a case where the mobile communication system is adjusted to facilitate cell reselection if the mobile terminal is in a high-speed movement state. In locations where many HeNBs are installed, the probability of being determined as a high-speed movement state increases. Therefore, in a location where many HeNBs are installed, the probability that the mobile communication system is adjusted to facilitate cell reselection is increased. As a result of this adjustment, the number of cell reselections of the mobile terminal increases more and more. The mobile terminal cannot recover from the situation where the number of cell reselections is large. The large number of cell reselections requires that the number of times that the mobile terminal receives broadcast information of a new cell be increased by the increase in cell reselection, resulting in a problem of increased power consumption of the mobile terminal. Non-Patent Document 4 discloses that a mobile terminal does not count reselection between the same two cells for detecting a moving state. Consider a case where the technology is applied to a location where many HeNBs are installed. As shown in FIG. 13B, since the reselection of the cell of the mobile terminal is not performed between the same cells, the reselection of the cell is counted for detecting the movement state. Therefore, the technique disclosed in Non-Patent Document 4 cannot solve the problem. Since the problem is a problem that occurs at a location where many HeNBs are installed, there is no suggestion of a problem in Non-Patent Document 7 where the introduction of HeNB is not considered.

  A solution in the first embodiment will be described below. It is disclosed that the mobile terminal does not count CSG cell reselection for detecting the mobile state. A specific example will be described below using the LTE system. A specific example of a method for determining whether a cell reselected by the mobile terminal (or a cell to be reselected) is a CSG cell will be described below. It is judged using a CSG indicator whether it is a CSG cell. The CSG indicator is a direction that is mapped to SIB1 as system information in the discussion of 3GPP and is broadcast from the base station (Non-Patent Document 8). If the CSG indicator is “TRUE”, the cell can be determined as a CSG cell. Determining whether or not the cell is a CSG cell by using the CSG indicator eliminates the need for additional information and can achieve the effect of effective use of radio resources. As another method, it is determined using a CSG-ID (CSG identity) whether the cell is a CSG cell. The CSG-ID is mapped to SIB1 as system information in the discussion of 3GPP, and is a direction broadcast from the base station (Non-Patent Document 8). If the CSG-ID is included, the cell can be determined as a CSG cell. Determining whether or not the cell is a CSG cell by using the CSG-ID eliminates the need for additional information and can achieve the effect of effective use of radio resources. Another method is to determine whether the cell is a CSG cell by using PCI split information. In the discussion of 3GPP, PCI is a direction to divide into CSG cell and non-CSG cell (Non-Patent Document 5). If it is a PCI for a CSG cell, the cell can be determined as a CSG cell. Determining whether or not the cell is a CSG cell by using PCI eliminates the need for additional information and can achieve the effect of effective use of radio resources.

  FIG. 14 shows an example of the operation. The LTE system will be described as a specific example. The figure shows a case where a CSG indicator is used as a method of determining whether or not a cell reselected by a mobile terminal is a CSG cell. In step ST1401, the serving cell notifies the user equipment being served thereby of the movement state parameter as system information. Specific examples of the movement state parameter include T_CRmax, N_CR_H, N_CR_M, and T_CRmaxHyst. In Step ST1402, the mobile terminal receives the movement state parameter from the serving cell. The mobile terminal starts T_CRmax and T_CRmaxHyst timers. The T_CRmax and T_CRmaxHyst timers are restarted when timed out. In step ST1403, the mobile terminal determines whether cell reselection has been performed. When cell reselection is not performed, the determination in step ST1403 is repeated. When cell reselection is performed, the mobile terminal makes a transition to step ST1405. Details of the determination of whether or not cell reselection in step ST1403 has been performed will be described later with reference to FIG.

  The base station reselected in step ST1404 reports the CSG indicator to the mobile terminals being served as system information. In Step ST1405, the mobile terminal receives the CSG indicator from the reselected base station, that is, the serving cell. The base station reselected in step ST1406 reports the cell ranking parameters to the mobile terminals being served as system information. Specific examples of cell ranking parameters include Q_Hyst and Q_offset. In Step ST1407, the mobile terminal receives the cell ranking parameter from the reselected base station, that is, the serving cell. The base station reselected in step ST1408 reports the adjustment parameter according to the cell ranking parameter speed to the mobile terminals being served as system information. Specific examples of the adjustment parameters according to the cell ranking parameter speed include a scaling factor for the high speed movement state for the measurement value adjustment parameter of the serving cell, a scaling factor for the medium speed movement state for the measurement value adjustment parameter of the serving cell, etc. There is. In Step ST1409, the mobile terminal receives an adjustment parameter corresponding to the speed of the cell ranking parameter from the reselected base station, that is, the serving cell.

  In step ST1410, the mobile terminal determines whether the reselection corresponds to selection between the same cells. When it corresponds to the selection between the same cells, it returns to step ST1403. When it does not correspond to the selection between the same cells, it changes to step ST1411. In Step ST1411, the mobile terminal determines whether or not the reselected cell is a CSG cell. As a specific example of the determination, the CSG indicator received in step ST1405 is used. As a specific example, if the CSG indicator indicates “TRUE”, it is determined that the cell is a CSG cell, and if it does not indicate “TRUE”, it is determined that the cell is not a CSG cell. If it is determined that the cell is a CSG cell, the process returns to step ST1403. When it judges that it is not a CSG cell, it changes to step ST1412. In Step ST1412, the mobile terminal adds 1 to the count value of the number of reselections for counting the number of cell reselections. In other words, 1 is added to the count value of the number of cell selections for detecting the movement state. Thereafter, the process returns to step ST1403. The count value is used for detecting the movement state of the mobile terminal. Thus, for example, the count value is reset (returned to “0”) when T_CRmax times out. Also, when T_CRmax times out, T_CRmax is resumed in order to continue detecting the moving state of the mobile terminal.

  Next, a specific example of detailed operation for determining whether or not cell reselection of a mobile terminal has been performed will be described using FIG. In step ST1501, it is determined whether or not to perform measurement for cell reselection. If it is determined that measurement for cell reselection is not performed, the determination in step ST1501 is repeated. If it is determined to perform measurement for cell reselection, the mobile terminal makes a transition to step ST1502. As a specific example of determining whether or not to perform cell reselection, when the reception level value of the serving cell is larger than the parameter (S_intrasearch), it is determined that measurement is not performed. On the other hand, when the reception level value of the serving cell is equal to or less than the parameter (S_intrasearch), it is determined that the measurement is performed. In step ST1502, it is determined whether the count value of the number of reselections for detecting the moving state has exceeded the medium speed threshold (N_CR_M). When it exceeds, it changes to step ST1503. If not, the process proceeds to step ST1508. In step ST1503, it is determined whether or not the count value of the number of reselections for detecting the moving state exceeds a high speed threshold (N_CR_H). When exceeding, a high-speed movement state is detected and it changes to step ST1504. If not, the medium speed movement state is detected and the process proceeds to step ST1506. In step ST1504, a transition is made to a high-speed movement state, and a transition is made to step ST1505. In step ST1505, the measurement value adjustment parameter of the serving cell is adjusted for high-speed movement. As a specific example, the measurement value adjustment parameter (Q_hyst) of the serving cell is multiplied by a scaling factor for a high-speed movement state for the measurement value adjustment parameter of the serving cell (Speed dependent scaling factor for Q_hyst for high Mobility state). Then, the process proceeds to step ST1511.

  In step ST1506, a transition is made to a medium speed movement state, and a transition is made to step ST1507. In step ST1507, the measurement value adjustment parameter of the serving cell is adjusted for medium speed movement. As a specific example, the measurement value adjustment parameter (Q_hyst) of the serving cell is multiplied by a scaling factor for a medium speed movement state for the measurement value adjustment parameter of the serving cell (Speed dependent scaling factor for Q_hyst for medium Mobility state). Then, the process proceeds to step ST1511. In step ST1508, it is determined whether or not the moving state of the mobile terminal is normal. As a specific example, it is determined whether a high-speed movement state and a medium-speed movement state are detected during T_CRmaxHyst. When not detecting, it changes to step ST1509. When it detects, it changes to step ST1511. In step ST1509, a transition is made to the normal movement state, and a transition is made to step ST1510. In step ST1510, the adjustment of the measurement value adjustment parameter of the serving cell according to the movement state of the mobile terminal is canceled. Then, the process proceeds to step ST1511.

  Cell ranking is performed in step ST1511. As a specific example, the serving cell and neighboring cell (s) are ranked using the value obtained by adding the tuning parameter (Q_Hyst) to the measured value of the serving cell and the value obtained by subtracting the tuning parameter (Q_offset) from the measured value of the neighboring cell. I do. Then, the process proceeds to step ST1512. In step ST1512, it is determined whether or not to perform cell reselection. As a specific example, if a new cell is ranked better (or higher) than the serving cell for a certain period of time (T_reselection) and has been camped on to the current serving cell for more than one second, cell re- Make a selection. If the condition is not satisfied, cell reselection is not executed.

  The following effects can be obtained by this embodiment. This embodiment makes it possible to realize that the mobile terminal does not count the reselection of the CSG cell for detecting the movement state. Even in the case of FIG. 13B where many HeNBs are installed, the number of reselections for detecting the moving state can be set to 0 as in FIG. 13A where many HeNBs are not installed. Thereby, although the mobile terminal has moved at a normal speed at a location where many HeNBs are installed, the number of reselections for detecting the mobile state increases by repeating cell reselection, and the mobile terminal's mobile state Can be prevented from being determined to be high speed. If it is determined that the mobile terminal is moving at a high speed, cell reselection will increase more and more under circumstances where the mobile communication system is adjusted to facilitate cell reselection. However, in this embodiment, it is possible to prevent the moving state of the mobile terminal due to the location where many HeNBs are installed from being determined to be high speed, and thus it is possible to prevent an increase due to this reselection. Preventing an increase in the number of cell reselections leads to a reduction in the number of times the mobile terminal receives broadcast information of a new cell. Therefore, the effect of reducing power consumption of the mobile terminal can be obtained. Further, even the method using the Doppler frequency measurement shown in Non-Patent Document 7 is considered to solve the problem of the first embodiment. However, the following effects can be obtained in the first embodiment. In the current 3GPP discussion, the movement state of a mobile terminal is determined by the number of cell reselections. Therefore, even when the method of Embodiment 1 is added, the increase in complexity of the mobile communication system is small. Therefore, from the viewpoint of increasing the complexity of the mobile communication system, there is an advantage that it is more advantageous than the implementation of the method of Non-Patent Document 7.

  Next, an operation method of mobility state parameters (T_CRmax, N_CR_H, N_CR_M, T_CRmaxHyst) when the mobile terminal performs cell reselection will be described. As the movement state parameter, a value notified from a serving cell before cell reselection may be used, or a value notified from a cell that newly becomes a serving cell after cell reselection may be used. At that time, the count value of the number of reselections for counting the number of times of reselection of the cell for detecting the movement state may be reset. When using the value notified from the cell that has newly become the serving cell after cell reselection, the movement state parameter values (eg, T_CRmax, T_CRmaxHyst) notified before cell reselection will be reset. An effect is obtained that can immediately reflect the radio wave environment in the serving cell. However, since the movement state parameter values notified before cell reselection (for example, T_CRmax, T_CRmaxHyst) are reset, if cell reselection occurs frequently or at short time intervals, the reset is repeated. As a result, there arises a problem that the actual movement state of the mobile terminal cannot be detected.

  To solve this problem, the following method is disclosed. When the movement state parameter value notified from the serving cell before cell reselection and the movement state parameter value notified from the serving cell after cell reselection are the same, parameter values from the serving cell before cell reselection (for example, T_CRmax, T_CRmaxHyst) ) Is not reset. Since the movement state parameter value notified from the serving cell before cell reselection and the movement state parameter value notified from the serving cell after cell reselection are the same, either parameter value may be used. Thus, by not resetting the parameter value, it is possible to eliminate repeated resetting even when cell reselection occurs frequently or at short time intervals. It is possible to detect the movement state of. If the movement state parameter value notified from the serving cell before cell reselection differs from the movement state parameter value notified from the serving cell after cell reselection, the movement state parameter value notified from the serving cell before cell reselection It should be used. By doing so, the parameter value is not reset, and the actual movement state of the mobile terminal can be detected.

  However, in this case, if the value notified from the serving cell at a certain point in time is used, it is possible that the radio environment of the newly selected cell will be completely different. The problem that it becomes impossible to detect is generated. In order to solve this problem, the time for using the movement state parameter value notified from the serving cell before cell reselection (at a certain time) is limited. As a specific example, a timer may be provided. As another example, T_CRmax and T_CRmaxHyst may be used as the timer. When the timer notified from the serving cell before cell reselection times out, the movement state parameter value notified from the serving cell before cell reselection is reset, and the movement state parameter value notified from the new cell is used. You can do it. At that time, the count value of the number of reselections for counting the number of times of reselection of the cell for detecting the movement state may be reset. The new cell may be a cell that has been reselected most recently before the timer times out. The serving cell at the time when the timer times out may be used. By setting the timer, it is possible to detect the movement state of the mobile terminal without being reset during the period of the timer, and it is possible to detect a more accurate movement state. In addition, after the timer has timed out, it is possible to use the movement state detection parameter from the new serving cell after cell reselection, so that the latest radio wave environment can be reflected, and even more accurate It becomes possible to detect the movement status of the mobile terminal.

  By using T_CRmax or T_CRmaxHyst as the timer, it is not necessary to provide a new parameter or notify the mobile terminal of a new parameter from the network, so that control of the network, mobile terminal, or system is prevented from becoming complicated. In addition, it is possible to suppress an increase in signaling capacity and use of useless radio resources. By using T_CRmax as a timer to limit the time to use the mobile state parameter value notified from the serving cell before cell reselection, it is possible to use the timer until time-out regardless of the mobile terminal's mobile state Therefore, the movement state of the mobile terminal can be detected more accurately.

  When the reselection of the CSG cell or the like is not counted for the movement state detection in the present embodiment (including modifications described later), when the timer notified from the serving cell before the cell reselection times out In addition, the cell movement state parameters which are not counted for the movement state detection may not be used. In this case, the cells other than the cells that are not counted for detecting the moving state may be the serving cell at the time when the timer times out or the cell that has been reselected immediately before the time out. By doing so, it becomes possible to detect the actual movement state of the mobile terminal and to prevent an increase in cell reselection. Preventing an increase in the number of cell reselections leads to a reduction in the number of times the mobile terminal receives broadcast information of a new cell. Therefore, the effect of reducing power consumption of the mobile terminal can be obtained.

  Next, a first modification will be described. When the method according to the above embodiment is used, the following problems occur. Consider a case where a macro cell is operated as a CSG cell. Consider a case where a mobile terminal is actually moving at a high speed in a location where a macro cell is operated as a CSG cell. Even if the mobile terminal performs reselection, it is determined that the cell reselected in step ST1411 of FIG. 14 is a CSG cell, so that the mobile terminal makes a transition to step ST1403 without making a transition to step ST1412. As a result, the count value of the number of reselections for detecting the moving state performed in step ST1412 of FIG. 14 does not increase. It is not determined that the medium speed threshold or the high speed threshold has been exceeded in step ST1502 or ST1503 in FIG. Thereby, in step ST1510 of FIG. 15, the adjustment according to the speed of the measurement value adjustment parameter of the serving cell is released. Therefore, in order to realize smooth cell reselection when the mobile terminal moves at high speed, parameters are adjusted to facilitate cell reselection when the mobile terminal is in a high-speed or medium-speed movement state. The problem that it becomes impossible to do.

  The solution in the first modification is shown below. It is disclosed that the mobile terminal switches the reselection of the CSG cell between “counting” and “not counting” for detecting the moving state. A specific example will be described below using the LTE system. The network side can switch the reselection of the CSG cell for the mobile terminal between “count” and “not count” for detecting the moving state. The switching information is notified from the base station. A specific example of the switching information is shown below. For example, if the switching information is “1 (eg, ON)”, it is instructed to count the reselection for detecting the movement state. Here, if it is “1 (eg, ON)”, it may be instructed to count the reselection for detecting the movement state regardless of whether the cell is a CSG cell or not. If it is “0 (for example, OFF)”, it is instructed to determine whether or not the reselection is counted for detecting the moving state depending on whether or not the cell is a CSG cell. That is, it is instructed to use the method of the first embodiment. Here, if it is “0 (for example, OFF)”, it may be instructed not to count the reselection for detecting the moving state regardless of whether the cell is a CSG cell or not. Although the case where the switching information is 1 bit is shown here, it may be a plurality of bits. Further, both ON and OFF may be notified, or it may be indicated only when it is ON and there is no notification of switching information. Alternatively, it may be indicated as OFF. If not, it may indicate ON.

The switching information notification method is shown below. It notifies the mobile terminal being served as broadcast information of the base station. You may make it notify with respect to the affiliated mobile terminal only as the alerting | reporting information of the macrocell operated as a CSG cell. As a result, it is possible to prevent an increase in the information amount of broadcast information of a normal macro cell that is not operated as a CSG cell. Thereby, the effect of effective utilization of radio resources can be obtained. Switching information is newly added as an information element of an existing MIB (Master Information Block) (Non-Patent Document 8) in the broadcast information. For example, in the LTE communication system, the MIB is mapped to the PBCH, so that it can be received at the initial stage of the search operation (specifically, step ST1204 in FIG. 12). Therefore, by mapping the switching information to the MIB information, it is possible to obtain the effects of preventing control delay and reducing power consumption.
Switching information is newly added as an information element of an existing SIB (System Information Block) (non-patent document 8) in the broadcast information BCCH. As an example, switching information is newly added as an information element of SIB1. When switching information is mapped to SIB1, the following effects can be obtained. For example, in an LTE communication system, SIB1 can be received at the initial stage of search (specifically, step ST1205 in FIG. 12).

  Therefore, by mapping the switching information to SIB1, the effects of preventing control delay and reducing power consumption can be obtained. Further, when a CSG indicator or CSG-ID (CSG identity) is used as a method for determining whether or not the cell is a CSG cell shown in Embodiment 1, the CSG indicator and CSG-ID (CSG identity) are mapped to SIB1. Therefore, the parameters for determining the movement state of the mobile terminal are mapped to the same block. This can be obtained by receiving system information having the same parameters for determining the movement state of the mobile terminal. Therefore, the effects of avoiding complexity of the mobile communication system and preventing control delay can be obtained. As another example, switching information is newly added as an information element of SIB2. When switching information is mapped to SIB2, the following effects can be obtained. In the current 3GPP, the setting of radio resources common to all mobile terminals being served by SIB2 is mapped to SIB2. Switching information that is information common to all mobile terminals is added to the SIB2 including the same parameters, so that the same parameters can be obtained by receiving the same system information. Therefore, the effects of avoiding complexity of the mobile communication system and preventing control delay can be obtained.

  As another example, switching information is newly added as an information element of SIB3. When switching information is mapped to SIB3, the following effects can be obtained. In the current 3GPP, a setting common to cell reselection is mapped to SIB3. Switching information, which is information common to cell reselection, is added to the SIB 3 including the same parameter, and the same parameter can be obtained by receiving the same system information. Therefore, the effects of avoiding complexity of the mobile communication system and preventing control delay can be obtained. As another example, switching information is newly added as an information element of SIB9. When mapped to SIB9, the following effects can be obtained. In the current 3GPP, the HeNB identifier (a home eNB identifier (HNBID)) is mapped to SIB9. Under such circumstances, it becomes possible for the mobile terminal to obtain parameters used in the process of obtaining information related to the HeNB by receiving the same system information, avoiding the complexity of operation of the mobile terminal, and control delay. The effect of prevention can be obtained.

  In addition, the switching information is mapped to the shared control channel (CCCH), dedicated control channel (DCCH), multicast control channel (MCCH), or multicast traffic channel (MTCH), which is a logical channel, and is also a transport channel. It may be mapped to a downlink shared channel (DL-SCH) and a physical downlink shared channel (PDSCH) which is a physical channel and notified to the mobile terminal. Broadcast information is information broadcast periodically. Therefore, reduction of the amount of broadcast information is an important issue from the viewpoint of effective use of radio resources. Therefore, when the switching information is notified using the downlink shared channel, the switching information can be notified to the mobile terminal without increasing the information amount of the broadcast information, and the effect of effective use of radio resources can be obtained.

  FIG. 16 shows an example of the operation. The LTE system will be described as a specific example. In FIG. 16, steps having the same numbers as those in FIG. Further, the process shown in FIG. 15 is the same in the first modification of the first embodiment, and thus the description thereof is omitted. The base station reselected in step ST1601 notifies switching information to the mobile terminals being served thereby. In step ST1602, the mobile terminal receives switching information from the reselected base station, that is, the serving cell. In step ST1603, the mobile terminal determines whether to count the reselection of the cell for detection of the movement state based on the switching information received in step ST1602. For example, if the switching information indicates ON and the reselection is instructed to be counted for detecting the moving state, the process proceeds to step ST1412. For example, if the switching information indicates OFF and the cell is a CSG cell, and if it is instructed to determine whether or not the reselection is counted for movement state detection, the process proceeds to step ST1411.

  The following effects can be obtained by this modification. In addition to the same effects as those of the first embodiment, the following effects can be obtained. When a macro cell is operated as a CSG cell, parameters can be adjusted to facilitate cell reselection in order to realize smooth cell reselection even when the mobile terminal actually moves at high speed. It has the effect of becoming possible.

  Next, a second modification will be described. When the method according to the above embodiment is used, the following problems occur. Consider a case where the HeNB is operated in the open access mode instead of the closed access mode. Consider a location where many HeNBs are installed as shown in FIG. 13B and the HeNB is operated in the open access mode. When the mobile terminal performs reselection, since it is determined that the cell reselected in step ST1411 of FIG. 14 is not a CSG cell, the mobile terminal makes a transition to step ST1412. In Step ST1412, the mobile terminal adds 1 to the count value of the number of reselections for counting the number of times of reselection of the cell for detecting the movement state. Therefore, under such a situation, the probability of being determined as a high-speed movement state or a medium-speed movement state increases. In such a location where many HeNBs are installed and the HeNB is operated as an open access mode, the problem described in the first embodiment occurs again.

  The solution in the modification 2 is shown below. It is disclosed that the mobile terminal does not count HeNB reselection for movement state detection. A specific example will be described below using the LTE system. A specific example of a method for determining whether or not a cell (or a cell to be reselected) reselected by the mobile terminal is a HeNB will be described below. It judges using the information of whether it is HeNB and whether the said cell is HeNB. As a specific example, the determination is made using information of SIB9. In the current 3GPP, the HeNB identifier (a home eNB identifier (HNBID)) is mapped to the SIB 9 (Non-Patent Document 8). If the HeNB identifier is mapped, the cell can be determined as a HeNB. On the other hand, if the HeNB identifier is not mapped, it can be determined that the cell is not a HeNB. Determining whether or not the HeNB is using the HeNB identifier eliminates the need for additional information and can achieve the effect of effective use of radio resources.

  FIG. 17 shows an example of the operation. The LTE system will be described as a specific example. In FIG. 17, steps having the same numbers as those in FIG. Further, since the process shown in FIG. 15 is the same in the second modification, the description thereof is omitted. The base station reselected in step ST1701 notifies the mobile terminal being served thereby of the system information. In Step ST1702, the mobile terminal receives system information from the reselected base station, that is, the serving cell. A mobile terminal judges whether the reselected cell is HeNB in step ST1703. As a specific example of the determination, the system information received in step ST1702 is used. As a specific example, if the HeNB identifier is mapped in the system information, the cell is determined to be a HeNB, and if the HeNB identifier is not mapped, it is determined that the cell is not a HeNB. When it is judged that it is HeNB, it returns to step ST1403. When it is judged that it is not HeNB, it changes to step ST1412. Further, if the SIB9 exists in the system information, the cell may be determined as a HeNB, and if the SIB9 does not exist in the system information, it may be determined that the cell is not a HeNB.

  The following effects can be obtained by this modification. Even when the HeNB is operated not in the closed access mode but in the open access mode, the same effect as in the first embodiment can be obtained. The first modification and the second modification described above can be used in combination.

  Next, a third modification of the above embodiment will be described. In this modification, another solution is disclosed for the same problem as in the first embodiment. It is disclosed that the mobile terminal does not count reselection to a cell with a small radius for detecting the moving state. A specific example will be described below using the LTE system. A specific example of a method for determining whether or not the radius of the cell reselected by the mobile terminal (or the cell to be reselected) is small will be described below. Radius information is notified from the base station, and the mobile terminal determines whether the radius of the reselected cell is small based on the received radius information. Specific examples of radius information are shown below. The actual radius length, the threshold value for determining that the cell has a small radius (specifically, if the radius length is smaller than the threshold value A, the cell is determined to have a small radius), and the radius is determined to be an intermediate cell. Threshold value (specifically, threshold A ≦ radius length <threshold B is determined to be an intermediate cell if the radius is satisfied, etc.), threshold value determined to be a cell having a large radius (specifically, radius If length ≧ threshold value B is satisfied, it is determined that the cell has a large radius, etc.). The threshold value is not limited to this, and may be one or more. Further, the threshold value may be static. By making the threshold value static, notification from the base station becomes unnecessary, and the effect of effective use of radio resources can be obtained. Not the actual radius length but the radius identification information is notified. Specific examples of the radius identification information include “small”, “medium”, and “large”. This is information indicating which group a cell belongs to by dividing the cell into groups (for example, small, medium, large) by radius. If there are three types of identification information, notification can be made with 2 bits. Therefore, by notifying the actual radius length but the radius identification information, the amount of information can be greatly reduced, and the effect of effective use of radio resources can be obtained. Here, an example in which the radius is divided into three groups (small, medium, and large) has been described, but it may be two groups (for example, small and large), or may be four or more groups. The method for notifying the radius information can use the same method as the switching information in the first modification of the first embodiment. Therefore, detailed description is omitted.

  FIG. 18 shows an example of the operation. The LTE system will be described as a specific example. In FIG. 18, steps having the same numbers as those in FIG. 14 execute the same or corresponding processes, and thus description of the portions having the same step numbers is omitted. Further, since the process shown in FIG. 15 is the same in the third modified example, the description thereof is omitted. The base station reselected in step ST1801 notifies radius information to the mobile terminals being served thereby. In step ST1802, the mobile terminal receives radius information from the reselected base station, that is, the serving cell. In Step ST1803, the mobile terminal determines whether or not the radius of the reselected cell is small. As a specific example of the determination, the radius information received in step ST1802 is used. The method for determining whether or not the radius is small using the radius information is as described above. If it is determined that the radius is small, the process returns to step ST1403. When it is determined that the radius is not small, the process proceeds to step ST1412.

  The following effects can be obtained by this modification. The effect that the problems of the first embodiment and the first modification and the second modification can be solved at a time can be obtained.

  In the method disclosed in Embodiment 1, the mobile terminal does not count the reselection of the CSG cell for the detection of the movement state. However, the reselection to the non-CSG cell and the CSG cell (even for the HeNB) Reselection to a good, small radius cell) may be counted separately. Calculation for deriving one value by counting the number of reselections for non-CSG cells and the number of reselections for CSG cells (may be for HeNB or cells with a small radius). An equation may be provided, and one value may be derived by inputting the number of reselection of each cell into the equation. As a specific example of the calculation formula, Na = N1 + r * N2 may be used. N1 is the number of reselections for a non-CSG cell, N2 is the number of reselections for a CSG cell (may be for HeNB or a cell with a small radius), r is an adjustment factor, and Na is derived One value to be played. r is an adjustment coefficient for adjusting the difference in radius between the CSG cell and the non-CSG cell. Since the radius of the CSG cell is smaller than that of the non-CSG cell, it is estimated that the number of cell reselections increases even if the mobile terminal is moving at the same speed. Therefore, an adjustment coefficient r is provided, and the value of N2 is adjusted by multiplying N2 by r. For example, it is assumed that the radius of the non-CSG cell is several kilometers and the radius of the CSG cell is several tens of meters. Therefore, r for adjusting the difference in radius is preferably set to 0.01 as the ratio of the CSG cell radius to the non-CSG cell radius, for example. r may be determined in advance or may be notified from the network to the mobile terminal. The notification method from the network to the mobile terminal may be mapped to MIB, SIB, SIB1, SIB2, and SIB3 in the same manner as the switching information of the first modification of the first embodiment. Detailed description is omitted. The calculation formula should be determined in advance. This is because notification is unnecessary and the effect of effective use of radio resources is obtained.

  Non-CSG cell reselection count and CSG cell reselection count (may be HeNB or may be a cell with a small radius), and use these two counts. The movement state is detected using one derived value Na. Specifically, the movement state parameter notified from the serving cell may be used. For example, ST1411 and ST1412 in FIG. 14 may be changed. In ST1411, it is determined whether the reselected cell is a CSG cell. If Yes, the count value of the number of reselection of CSG is incremented by 1, and the process proceeds to ST11412. Also, in ST1411, it is determined whether the reselected cell is a CSG cell, and if No, the count value of the number of reselections of non-CSG is incremented by 1, and the process proceeds to ST1412. In ST1412, two count values and r are input to the above formula to derive Na. Note that r is determined in advance or is notified to the mobile terminal from the network in advance. Based on the derived Na, whether to reselect a cell is determined in ST1403.

  Thus, by counting the number of cell reselections of CSG cells, it is possible to detect the moving speed of the mobile terminal even when the mobile terminal is in a situation where many CSG cells are isolated, for example. Become. Further, even when a large number of CSG cells are arranged in a non-CSG cell and the mobile terminal is moving between the multiple CSG cells in the non-CSG cell, the moving speed of the mobile terminal is detected. It becomes possible.

You may have separately a movement state parameter for CSG cells and non-CSG cells (it may be HeNB use or a cell with a small radius). In the above, it disclosed that counting the cell reselection frequency of a non-CSG cell and a CSG cell separately. The movement state parameter for the non-CSG cell is used to detect the movement state from the number of cell reselections of the non-CSG cell, and the movement state for the CSG cell is used to detect the movement state from the number of cell reselections of the CSG cell. Use parameters. As a specific example, the moving state parameters for non-CSG cell (T_CRmax_nC, N_CR_H _ nC, N_CR_M _ nC, T_CRmaxHyst _ nC), the movement state parameters for CSG cells (T_CRmax_C, N_CR_H _ C, N_CR_M _ C, T_CRmaxHyst _ C). By doing so, it is possible to reduce a movement state detection error due to a difference in radius between the CSG cell and the non-CSG cell. Moreover, you may make it have one or more among movement state parameters separately as needed. By sharing a part, it is possible to obtain an effect of effective use of radio resources and reduction of processing of the mobile terminal. As a method for notifying the mobile terminal of the movement state parameter for the non-CSG cell and the movement state parameter for the CSG cell, there is a method of notifying both parameters from the network to the mobile terminal via one cell (serving cell). is there.

  As another method, only one set of movement state parameters is notified from the network to the mobile terminal via one cell (serving cell), and the movement state parameters for the non-CSG cell are transmitted from the non-CSG cell. There is a method of notifying the mobile state parameter for the CSG cell from the CSG cell. In the case of this method, since the movement state parameters notified from the network to the mobile terminal through one cell are one set, a more accurate mobile terminal can be obtained without increasing the signaling amount and the processing amount of the mobile terminal. The effect that it becomes possible to perform a movement condition detection is acquired. One parameter name to be notified may be set as one. In that case, which parameter should be determined depending on which cell is notified. CSG cells can be grouped by CSG-ID, but CSG cells with the same CSG-ID may notify the same mobility state parameter. As a result, it is possible to flexibly cope with the installation situation, for example, when the same CSG-ID is used in one company.

  If the cell before reselection is a non-CSG cell for detecting the movement state of the mobile terminal, the mobility state parameter for the non-CSG cell is used, and if the cell before reselection is a CSG cell, Use moving state parameters. The number of reselections of the non-CSG cell and the CSG cell is separately counted, and if the cell before reselection is a non-CSG cell, the mobility state parameter for the non-CSG cell and the number of reselections of the non-CSG cell The moving state is detected from the above. If the cell before reselection is a CSG cell, the movement state is detected from the movement state parameter for the CSG cell and the number of reselections of the CSG cell. From the two movement states detected as described above, one that is closer to the movement state of the mobile terminal is selected. Which one is selected as closer to the moving state of the mobile terminal may be determined in advance, or may be notified from the network to the mobile terminal. For example, the faster one of the two detected movement states is selected as being closer to the movement state of the mobile terminal. The cell reselection determination is performed according to the selected movement state. By doing so, an effect is obtained in which the movement state of the mobile terminal can be detected more accurately. In the above description, it has been disclosed to select one of the detected two moving states that is closer to the moving state of the mobile terminal. However, for example, when the selected mobile state is based on the reselection count of the CSG cell, and the serving cell at the time of cell reselection is a non-CSG cell, it is derived from the CSG cell. The scaling factor is used for the cell reselection determination from the non-CGS cell. In such a case, there is a problem that cell reselection may not be accurately performed depending on the actual movement status of the mobile terminal. In order to solve this problem, the following method is disclosed.

  If the cell before reselection is a non-CSG cell for detecting the movement state of the mobile terminal, the mobility state parameter for the non-CSG cell is used. Use parameters. The number of reselections of the non-CSG cell and the CSG cell is separately counted, and if the cell before the reselection is a non-CSG cell, the mobility state parameter for the non-CSG cell and the number of reselections of the non-CSG cell The movement state is detected from the above, and reselection determination from the non-CSG cell is performed. If the cell before reselection is a CSG cell, the mobile state is detected from the movement state parameter for the CSG cell and the reselection frequency of the CSG cell, and reselection determination from the CSG cell is performed. That is, the cell reselection operation of the non-CSG cell and the cell reselection operation of the CSG cell are performed in parallel. HeNB / HNB is required not only to complement communication outside the coverage of the macro cell, but also to support various services. In addition, a large number of HeNB / HNBs may be installed. In addition, the cell radius of HeNB / HNB is expected to be smaller than the cell radius of the macro cell. Thus, various variations can be considered in the arrangement of base stations as a mobile communication system. According to the method disclosed above, it is possible to perform the non-CSG cell reselection operation and the CSG cell reselection operation in parallel under such circumstances. Thereby, the effect that a mobile communication system can perform flexible control can be acquired.

  The operation method of the movement state parameter disclosed in the first embodiment can also be applied to the method disclosed above. When the movement state parameter value notified from the serving cell before cell reselection is different from the movement state parameter value notified from the serving cell after cell reselection, the movement state parameter value notified from the serving cell before cell reselection is used. Disclosed is a method for limiting the time to use the movement state parameter value notified from the serving cell before cell reselection (at a certain time). In this case, if the serving cell at the time when the timer times out is a non-CSG cell, the re-selection operation for the non-CSG cell may use the movement state parameter of the newly selected non-CSG cell, For the reselection operation for the CSG cell, the movement state parameter of the most recently selected CSG cell may be used. On the other hand, if the serving cell at the time when the timer times out is a CSG cell, the re-selection operation for the non-CSG cell may use the movement state parameter of the most recently selected non-CSG cell. For the reselection operation, the movement state parameter of the newly selected CSG cell may be used. In this way, even when many future CSG cells or HeNB / HNBs are installed, it becomes possible to reflect the latest radio wave environment regardless of the cell installation status, and even more accurate mobile terminal It is possible to detect the movement status.

  Although the method disclosed above has been described for the case of a CSG cell and a non-CSG cell, it can also be applied to a HeNBn and a cell having a small radius. The disclosed method can also be applied to the first embodiment including a modification.

Embodiment 2. FIG.
A problem to be solved in the second embodiment will be described. When a mobile terminal that moves at a high speed selects a cell with a small radius, it immediately falls out of coverage, and cell reselection occurs again if it is waiting (during idle). If a call is in progress, handover will occur again. If cell reselection is repeated, the number of times that the mobile terminal receives broadcast information of a new cell is required to be increased by the increase in cell reselection, resulting in a problem of increased power consumption of the mobile terminal. If the handover is repeated, the control signal between the base station and the mobile terminal increases, and there are problems of effective use of radio resources, an increase of control delay as a mobile communication system, and an increase of power consumption of the mobile terminal. Arise.

  A solution in the second embodiment will be described below. Depending on the moving state of the mobile terminal, cells that can be reselected (may include cell selection) are limited, or cells that can be handed over are limited. A specific example will be described below using the LTE system. A specific example of a method for limiting cells is shown below. Information indicating whether the cell is a CSG cell is used. As a specific example of a method for determining whether the cell is a CSG cell, the “CSG indicator”, “CSG-ID”, and the like described in Embodiment 1 can be used. Additional information becomes unnecessary, and the effect of effective use of radio resources can be obtained. A specific example of the cell limiting operation is shown below. A mobile terminal in a high-speed movement state can perform cell reselection, cell selection, or handover only to a cell determined to be a non-CSG cell. A mobile terminal in a medium-speed movement state and a normal movement state can perform cell reselection, cell selection, or handover even in a CSG cell or non-CSG cell. Here, an example in which the movement state is divided into three groups (high speed, medium speed, normal) has been described, but two groups (for example, high speed, normal) may be used, or four or more groups may be used. good. Further, the combination of information regarding whether or not the mobile state is a CSG cell is not limited to the above specific example. A specific example of a method for detecting the movement state of the mobile terminal is shown below. A method based on the number of cell reselections of a mobile terminal that is currently being standardized by 3GPP, a method disclosed in Embodiment 1, and a method based on Doppler frequency measurement described in Non-Patent Document 7 A method based on the global positioning system (GPS) based on the position information of the mobile terminal can be applied.

  A specific example of detailed operation for limiting reselectable cells according to the moving state of the mobile terminal will be described with reference to FIG. As a specific example, cell reselection in the LTE system will be described. In FIG. 19, steps having the same numbers as those in FIG. 12 perform the same or corresponding processes, and therefore description of the portions having the same step numbers is omitted. In Step ST1901, the mobile terminal determines whether there is a cell reselection candidate cell. If there is a cell reselection candidate cell, the mobile terminal makes a transition to step ST1902. When there is no cell reselection candidate, the process returns to step ST1201. For example, when the following two conditions are satisfied, the mobile terminal sets a new cell as a cell reselection candidate. (1) A new cell is ranked better (or higher) than the serving cell for a certain period (T_reselection). (2) One second or more has passed since the current serving cell was camped on. In Step ST1902, the mobile terminal receives the broadcast information of the cell reselection candidate cell. For example, a CSG indicator and CSG-ID are mapped to SIB1 in the broadcast information.

  In step ST1903, the mobile terminal determines the movement state of the own mobile terminal. If it is determined that the movement state is the high-speed movement state, the mobile terminal makes a transition to step ST1904. If it is determined that the vehicle is in the medium speed movement state or the normal movement state, the mobile terminal makes a transition to step ST1905. In addition to the movement state parameter, a cell limitation parameter may be newly added. As a specific example, a cell limiting parameter such as N_CR_CSG is reported from the base station. The same method as the switching information in the first modification of the first embodiment can be used as the cell limiting parameter notification method. Therefore, detailed description is omitted. As a specific example of the operation, the number of cell reselections during a certain period (T_CRmax or dedicated to cell limiting parameters) of the own mobile terminal may be the cell limiting parameter (N_CR_CSG). If it exceeds, the process moves to step ST1904 to limit the cells. If the number of cell reselections does not exceed the cell limiting parameter (N_CR_CSG), the mobile terminal makes a transition to step ST1905 so as not to limit the cells. HeNB / HNB is required not only to complement communication outside the coverage of the macro cell, but also to support various services. In addition, a large number of HeNB / HNBs may be installed.

  In addition, the cell radius of HeNB / HNB is expected to be smaller than the cell radius of the macro cell. Thus, various variations can be considered in the arrangement of base stations as a mobile communication system. Under such circumstances, by newly adding a cell limiting parameter as described above, it is possible to obtain an effect that the mobile communication system can perform flexible control. As a specific example, when the moving speed of the mobile terminal exceeds 30 km per hour (may be 30 km or more), the mobile terminal moves to step ST1904 to limit the cells. When the moving speed of the mobile terminal is 30 km / h or less (may be less than 30 km), the mobile terminal moves to step ST1905 so as not to limit the cells. As shown in Non-Patent Document 9, 3GPP discusses support of a mobile terminal moving at a speed of 30 km per hour as a required specification of HeNB (HNB). Therefore, depending on the HeNB, a mobile terminal moving at a high speed exceeding 30 km / h is not supported, that is, a case where communication is impossible is considered. Under such circumstances, determining whether to limit the cell based on whether the moving speed of the mobile terminal exceeds 30 km per hour is that the mobile terminal is in a HeNB that does not support a mobile terminal moving at high speed. By performing cell reselection or the like, an effect of preventing communication from becoming impossible can be obtained. The speed used for judgment here is not limited to 30 km.

  In Step ST1904, the mobile terminal determines whether or not the reselection candidate cell is a CSG cell. A specific example of the determination uses the CSG indicator in the broadcast information received in step ST1902. As a specific example, if the CSG indicator indicates “TRUE”, it is determined that the cell is a CSG cell, and if it does not indicate “TRUE”, it is determined that the cell is not a CSG cell. As another specific example of the determination, if the CSG-ID is included in the broadcast information received in step ST1902, the cell can be determined as a CSG cell. On the other hand, if the CSG-ID is not included in the broadcast information, it can be determined that the cell is not a CSG cell. If it is determined that the cell is a CSG cell, the process returns to step ST1201. When it determines that it is not a CSG cell, it changes to step ST1905. In Step ST1905, the mobile terminal reselects the reselection candidate cell. The operation in the case of cell selection and the operation in the case of determining the handover destination on the mobile terminal side are the same as or equivalent to those in FIG.

  The following effects can be obtained by this embodiment. For example, when the mobile terminal is in a high-speed moving state, the CSG cell is not reselected, selected, or handed over. This will be described using a specific example. Consider a case where the mobile terminal 2005 is moving at high speed as indicated by an arrow in a location where many CSG cells (2002, 2003, 2004) are installed in the coverage of the macro cell 2001 as shown in FIG. In this case, unless Embodiment 2 is used, reselection or handover with the CSG cell 2002, CSG cell 2003, and CSG cell 2004 will be repeated. This causes problems such as an increase in power consumption of the mobile terminal as shown in the problem of the second embodiment. On the other hand, by using the second embodiment, even in such a case, since CSG cell 2003 and CSG cell 2004 are determined as CSG cells in step ST1904 in FIG. No cell reselection or handover to the CSG cell 2004 is performed. As a result, the mobile terminal 2005 performs reselection or handover to the macro cell 2001, for example. As described above, by using the second embodiment, it is possible to prevent repeated reselection of cells, and an effect of reducing power consumption of the mobile terminal can be obtained. In addition, it is possible to prevent repeated handovers, and it is possible to obtain effects such as effective utilization of radio resources, reduction of control delay as a mobile communication system, and reduction of power consumption of a mobile terminal.

  Next, a first modification according to the above embodiment will be described. In this modification, another solution is disclosed for the same problem as in the second embodiment. The solution in this modification is shown below. Similar to the second embodiment, the cells that can be reselected (including cell selection) are limited or the cells that can be handed over are limited according to the movement state of the mobile terminal. A specific example will be described below using the LTE system. A specific example of a method for limiting cells is shown below. Information indicating whether the cell is a CSG cell is used. As a specific example of a method for determining whether or not the cell is a CSG cell, “PCI split information can be used as described in the first embodiment. Additional information is unnecessary, and an effect of effective use of radio resources can be obtained. Since a specific example of the cell limiting operation and a specific example of the method of detecting the movement state of the mobile terminal are the same as those in the second embodiment, the description thereof is omitted.

  A specific example of detailed operation for limiting reselectable cells according to the moving state of the mobile terminal will be described with reference to FIG. As a specific example, cell reselection in the LTE system will be described. In FIG. 21, steps having the same numbers as those in FIGS. 12 and 19 execute the same or corresponding processes, and thus description of the same step numbers is omitted. In step ST2101, the mobile terminal obtains PCI split information (sometimes referred to as a CSG PCI range as a PCI set (one or a plurality of PCIs) reserved for a CSG cell). Judge whether or not to have. In the current 3GPP discussion, PCI split information is mapped to SIB4 in the broadcast information of the CSG cell. Whether or not PCI split information is broadcast from the non-CSG cell may be either. When having PCI split information, the mobile terminal makes a transition to step ST2102. When there is no PCI split information, the mobile terminal makes a transition to step ST1202. In step ST2102, the mobile terminal determines the movement state of the own mobile terminal. If it is determined that the movement state is a high-speed movement state, the mobile terminal makes a transition to step ST2103. If it is determined that the vehicle is in the medium speed movement state or the normal movement state, the process proceeds to step ST1202. A mobile terminal judges whether the said cell is a CSG cell in step ST2103. As a specific example of the determination, it is determined whether the PCI detected in step ST1201 is for a CSG cell using PCI split information. If the detected PCI is for a CSG cell, it is determined that the cell is a CSG cell, and the process returns to step ST1201. If the detected PCI is not for a CSG cell, it is determined that the cell is a non-CSG cell, and the mobile terminal makes a transition to step ST1202. The operation in the case of cell selection and the operation in the case of determining the handover destination on the mobile terminal side are the same as or equivalent to those in FIG.

  The following effects can be obtained by this embodiment. In addition to the same effects as those of the second embodiment, the following effects can be obtained. If the mobile terminal in the high-speed movement state obtains PCI split information, the cell reselection operation of the CSG cell is performed at a fast search operation stage of PCI detection (step ST1201 in FIG. 12, step 1201 in FIG. 21). It is possible to cancel the cell selection operation and the handover operation. As a result, the search operation of the mobile terminal in the fast moving state is wasted, specifically, the cell reselection candidate, the cell selection candidate, and the handover destination candidate cell are CSG cells (step ST1202, step ST1202, FIG. 19). ST1203, step ST1901, etc.) can be reduced. This can provide the effect of reducing power consumption of the mobile terminal and the effect of preventing control delay.

  Next, a second modification according to the above embodiment will be described. When the method of Embodiment 2 is used, the following problems occur. Consider a case where a macro cell is operated as a CSG cell. Consider a case where a mobile terminal is actually moving at a high speed in a location where a macro cell is operated as a CSG cell. Since the cell is a macro cell, the problem described in Embodiment 2 does not occur even when a mobile terminal in a high-speed movement state performs cell reselection, cell selection, or handover. On the contrary, using the method of the second embodiment, because the macro cell is a CSG cell, by excluding the cell from the cell reselection destination, the cell selection destination, or the handover destination, the mobile terminal is out of service area, that is, communication. The problem of becoming impossible occurs.

  The solution in the second modification is shown below. The network side can switch to a mobile terminal by limiting the cells that can be reselected (including cell selection) or limiting the cells that can be handed over. The switching information is notified from the base station. A specific example will be described below using the LTE system. A specific example of the switching information is shown below. For example, if the switching information is “1 (eg, ON)”, it is instructed to limit the cells. If it is “0 (for example, OFF)”, it is instructed not to limit the cell (release the limitation). Although the case where the switching information is 1 bit is shown here, it may be a plurality of bits. Further, both ON and OFF may be notified, or it may be indicated only when it is ON and there is no notification of switching information. Alternatively, it may be indicated as OFF. If not, it may indicate ON. As the switching information notification method, the same method as the switching information of the first modification of the first embodiment can be used. Therefore, detailed description is omitted.

  FIG. 22 shows an example of the operation. The LTE system will be described as a specific example. 22, steps having the same numbers as those in FIGS. 12 and 19 execute the same or corresponding processes, and thus description of the same step numbers is omitted. In step ST2201, the mobile terminal determines whether or not to limit cells based on the switching information received from the cell reselection candidate cells. For example, if the switching information indicates ON and it is instructed to limit the cells, the process proceeds to step ST1903. For example, if the switching information indicates OFF and it is instructed not to limit cells, the process proceeds to step ST1905. The operation in the case of cell selection and the operation in the case of determining the handover destination on the mobile terminal side are the same as or equivalent to those in FIG.

  The following effects can be obtained by this modification. In addition to the same effects as those of the second embodiment, the following effects can be obtained. When the macro cell is operated as a CSG cell, the macro cell can be a cell reselection destination, a cell selection destination, or a handover destination even when the mobile terminal actually moves at high speed. This prevents the communication from being disabled and enables smooth movement.

  Next, a third modification according to the above embodiment will be described. When the method of Embodiment 2 is used, the following problems occur. Consider a case where the HeNB is operated in the open access mode instead of the closed access mode. As shown in FIG. 20, many HeNBs (base station 2002, base station 2003, base station 2004) are installed, and the mobile terminal is actually moving at a high speed in a location where the HeNB is operated as an open access mode. Think about the case. When the mobile terminal performs reselection, since it is determined that the cell reselected in step ST1904 of FIG. 19 is not a CSG cell, the mobile terminal makes a transition to step ST1905. In Step ST1905, the mobile terminal performs cell reselection to the cell (HeNB operated as the open access mode). In such a location where many HeNBs are installed and the HeNB is operated as an open access mode, the problem described in the second embodiment occurs again.

  The solution in the third modification is shown below. Depending on the moving state of the mobile terminal, cells that can be reselected (may include cell selection) are limited, or cells that can be handed over are limited. A specific example will be described below using the LTE system. A specific example of a method for limiting cells is shown below. Information on whether or not it is a HeNB is used. As a specific example of the method for determining whether or not the HeNB is used, the identifier of the HeNB shown in the second modification of the first embodiment can be used. Additional information becomes unnecessary, and the effect of effective use of radio resources can be obtained. A specific example of the cell limiting operation is shown below. A mobile terminal in a high-speed movement state can perform cell reselection, cell selection, or handover only to a cell that is determined not to be a HeNB. The mobile terminal in the medium speed movement state and the normal movement state can perform cell reselection, cell selection, or handover even in a cell that is not HeNB or HeNB. Here, an example in which the movement state is divided into three groups (high speed, medium speed, normal) has been described, but two groups (for example, high speed, normal) may be used, or four or more groups may be used. good. Moreover, the combination of the information on whether or not the mobile state is a HeNB is not limited to the above specific example. A specific example of a method for detecting the movement state of the mobile terminal is shown below. A method based on the number of cell reselections of a mobile terminal that is currently being standardized by 3GPP, a method disclosed in Embodiment 1, and a method based on Doppler frequency measurement described in Non-Patent Document 7 A method based on the global positioning system (GPS) based on the position information of the mobile terminal can be applied.

  A specific example of detailed operation for limiting reselectable cells according to the moving state of the mobile terminal will be described with reference to FIG. As a specific example, cell reselection in the LTE system will be described. In FIG. 23, steps having the same numbers as those in FIGS. 12 and 19 execute the same or corresponding processes, and thus description of the same step numbers is omitted. A mobile terminal judges whether the reselected cell is HeNB in step ST2301. As a specific example of the determination, the notification information received in step ST1902 is used. As a specific example, if the HeNB identifier is mapped in the broadcast information, the cell is determined to be a HeNB, and if the HeNB identifier is not mapped, it is determined that the cell is not a HeNB. When it is judged that it is HeNB, it returns to step ST1201. When it is judged that it is not HeNB, it changes to step ST1905. Further, if SIB9 exists in the system information in the broadcast information, the cell may be determined as HeNB, and if SIB9 does not exist in the system information in the broadcast information, it may be determined that the cell is not a HeNB cell. The operation in the case of cell selection and the operation in the case of determining the handover destination on the mobile terminal side are the same as or equivalent to those in FIG.

  The following effects can be obtained by this modification. Even when the HeNB is operated not in the closed access mode but in the open access mode, the same effect as in the second embodiment can be obtained. Note that Modification 2 of Embodiment 2 and Modification 3 of Embodiment 2 can be used in combination.

  Next, a fourth modification according to the above embodiment will be described. In this modification, another solution is disclosed for the same problem as in the second embodiment. Depending on the moving state of the mobile terminal, cells that can be reselected (may include cell selection) are limited, or cells that can be handed over are limited. A specific example will be described below using the LTE system. A specific example of a method for limiting cells is shown below. Cell radius information is used to limit cells. A specific example of the cell radius information is the same as the content shown in the third modification of the first embodiment, and thus the description thereof is omitted. The method for notifying the radius information can use the same method as the switching information in the first modification of the first embodiment. Therefore, detailed description is omitted. A specific example of the cell limiting operation is shown below. A mobile terminal in a high-speed movement state can perform cell reselection, cell selection, or handover only to a cell that is determined to have a large radius. The mobile terminal in the medium speed movement state can perform cell reselection, cell selection, or handover only to a cell having a large radius or a cell determined to be an intermediate cell.

  A mobile terminal in a normal moving state can reselect, cell select, or perform handover for any radius information cell (that is, a cell with a large radius, an intermediate cell, or a cell determined to be a small cell). And Here, an example in which the radius is divided into three groups (small, medium, and large) has been described, but it may be two groups (for example, small and large), or may be four or more groups. Here, an example in which the movement state is divided into three groups (high speed, medium speed, normal) has been described, but two groups (for example, high speed, normal) may be used, or four or more groups may be used. good. Further, the combination of the moving state and the radius information is not limited to the above specific example. A specific example of a method for detecting the movement state of the mobile terminal is shown below. A method based on the number of cell reselections of a mobile terminal that is currently being standardized by 3GPP, a method disclosed in Embodiment 1, and a method based on Doppler frequency measurement described in Non-Patent Document 7 A method based on GPS (Global Positioning System) based on the location information of mobile terminals can be applied.

  A specific example of detailed operation for limiting reselectable cells according to the moving state of the mobile terminal will be described with reference to FIG. As a specific example, cell reselection in the LTE system will be described. In FIG. 24, steps having the same numbers as those in FIGS. 12 and 19 execute the same or corresponding processes, and therefore, description of portions having the same step numbers is omitted. A mobile terminal receives the radius information of a cell reselection candidate cell in step ST2401. In step ST2402, the mobile terminal determines the movement state of the own mobile terminal. If it is determined that the movement state is a high-speed movement state, the mobile terminal makes a transition to step ST2403. If it is determined that the vehicle is in the medium speed movement state, the process proceeds to step ST2404. Or if it determines that it is a normal movement state, it will change to step ST1905. For the determination of the movement state, the same processing as that described in step ST1903 can also be used. In step ST2403, the mobile terminal determines whether or not to reselect a cell. A specific example of the determination uses the radius information received in step ST2401. As a specific example, it is determined whether or not the cell is determined to be a large cell by the radius information. If it is determined by the radius information that the cell is large, the mobile terminal makes a transition to step ST1905. If the radius information does not determine that the cell is large, the process returns to step ST1201.

  In Step ST2404, the mobile terminal determines whether or not to reselect a cell. A specific example of the determination uses the radius information received in step ST2401. As a specific example, it is determined whether or not the cell is determined to be a large cell or an intermediate cell based on the radius information. If it is determined by the radius information that the cell is a large cell or an intermediate cell, the mobile terminal makes a transition to step ST1905. If the radius information is not determined to be a large cell or an intermediate cell, the process returns to step ST1201. The operation in the case of cell selection and the operation in the case of determining the handover destination on the mobile terminal side are the same as or equivalent to those in FIG.

  The following effects can be obtained by this modification. The effect that the problems of the second embodiment, the second modification of the second embodiment, and the third modification of the second embodiment can be solved at a time can be obtained.

Next, a fifth modification of the above embodiment will be described. This modification discloses a solution for the case where the network side determines the handover destination for the same problem as in the second embodiment. The solution in this modification is shown below. Information on the movement state of the mobile terminal is notified to the network side (base station), and the base station limits the cells that can be handed over according to the movement state of the mobile terminal. A specific example will be described below using the LTE system. Specific examples of the movement state information are shown below.
(1) The actual moving speed of the mobile terminal, for example, the speed per hour may be notified from the mobile terminal to the base station (serving cell). Based on the actual movement speed, the movement state of the mobile terminal is determined on the network side. As a specific example, a threshold value determined as a normal movement state (specifically, a determination is made as a normal movement state if the movement speed <threshold a is satisfied), a threshold value determined as a medium speed movement state (as a specific example) Is determined to be a medium speed moving state if threshold a ≦ moving speed <threshold b is satisfied), and a threshold value determined to be a high speed moving state (specifically, if moving speed ≧ threshold b is satisfied, For example). By changing the threshold value on the network side, it is possible to obtain an effect that the movement state of the mobile terminal can be determined flexibly. The threshold may be static.
(2) The mobile state may be notified from the mobile terminal to the base station. A specific example of the method for detecting the movement state of the mobile terminal is the same as that in the second embodiment, and thus description thereof is omitted. Further, the threshold values a and b in (1) may be notified from the serving cell to the mobile terminal, and the mobile terminal may determine the moving state. This method can also be used in the second embodiment. Notify the actual moving speed, notify the moving state. Specific examples of the moving state include “normal moving state”, “medium speed moving state”, and “high speed moving state”. If there are three types of identification information, notification can be made with 2 bits. Therefore, by notifying the actual moving speed but not the moving state, the amount of information can be greatly reduced, and the effect of effective use of radio resources can be obtained.
Here, an example of dividing the movement state into three groups (normal movement state, medium speed movement state, and high speed movement state) has been described, but two groups (normal movement state, high speed movement state) may be used, There may be four or more groups.

  A specific example of the method for notifying the mobile state information from the mobile terminal to the base station (serving cell) is shown below. The movement state information is mapped to the logical control channel (CCCH) or dedicated control channel (DCCH), and the transport channel is the uplink shared channel (UL-SCH) and the physical channel is the physical uplink shared. It may be mapped to a channel (PUSCH) and notified from the mobile terminal to the serving base station. The uplink shared channel (UL-SCH) is a channel in which radio resources are allocated from the serving cell to the mobile terminal in response to a scheduling request from the mobile terminal to the serving cell. Since notification is possible depending on the request of the mobile terminal, the restriction on the notification timing is loose. Therefore, it is possible to obtain an effect that a mobile communication system capable of flexible control can be constructed by notifying information on the movement state using the uplink shared channel.

A specific example of the timing for notifying the mobile state information from the mobile terminal to the base station (serving cell) is shown below.
(1) The mobile terminal periodically notifies the base station of information on the moving state. The period may be static or may be notified from the network side to the mobile terminal. As a notification method from the serving cell of the period to the mobile terminal, the same method as the switching information of the first modification of the first embodiment can be used. Therefore, detailed description is omitted. Periodic notification of movement status information makes it possible to re-receive in the next cycle even if a reception error occurs at a certain timing. The effect that a system can be constructed can be obtained.
(2) When the mobile terminal changes the mobile state to the base station, the mobile terminal notifies the mobile state information. The number of notifications can be reduced as compared with the case (1) in which the information on the movement state is periodically notified. Therefore, the effect of effective use of radio resources can be obtained.
(3) When the mobile terminal makes a measurement report (or event notification) to the base station, the mobile terminal notifies the mobile state information. In some cases, the base station receives a measurement report and determines whether or not to hand over the mobile terminal. In this modified example in which the base station limits the cells that can be handed over according to the movement state of the mobile terminal, the measurement report and the movement state information of the mobile terminal, which are information used together, can be received together. . Thereby, the effect of avoiding the complexity of the mobile communication system and preventing the control delay can be obtained. Further, the same effect can be obtained by adding information on the movement state as an information element in the measurement report. Furthermore, the measurement report and the movement state information can be notified by one scheduling request, and the effect of effective use of radio resources can be obtained.

  FIG. 25 shows an example of the operation. The LTE system will be described as a specific example. A mobile terminal notifies a measurement report to a serving cell in step ST2501. In step ST2502, the serving cell receives a measurement report from the mobile terminal. In Step ST2503, the mobile terminal notifies the serving cell of information on the movement state of the mobile terminal. In step ST2504, the serving cell receives information on the movement state of the mobile terminal from the mobile terminal. In step ST2505, the serving cell determines whether to perform handover. Using a specific method such as the second embodiment, the first modification 1, the third modification, the fourth modification, or the like, a determination is made to limit the cells that can be handed over according to the movement state of the mobile terminal. . If it is determined that a handover is to be performed, the mobile terminal makes a transition to step ST2506. If it is determined that the handover is not performed, the process is terminated. In step ST2506, the serving cell performs handover preparation on the entire network side. In Step ST2507, the serving cell notifies the mobile terminal of a handover instruction. In Step ST2508, the mobile terminal receives a handover instruction from the serving cell.

  The following effects can be obtained by this embodiment. Even when the handover destination is determined on the network side, the cells that can be handed over can be limited according to the movement state of the mobile terminal. Therefore, the same effect as in the second embodiment can be obtained.

  In the present embodiment, it has been shown that cells that can be reselected (or cell selection may be included) are limited or cells that can be handed over are limited according to the moving state of the mobile terminal. The method disclosed in the first embodiment (including modifications) may be used as a method for detecting the movement state of a mobile terminal. As described in the first embodiment, when a conventional method is used as a mobile terminal movement state detection method, in a situation where many CSG cells, HeNBs, or cells having a small radius are installed, the mobile terminal is actually May be determined to be in a high-speed movement state even though it is not moving at high speed. When the method disclosed in this embodiment is used in such a situation, the mobile terminal cannot reselect to a CSG cell, HeNB, or a cell with a small radius even though the mobile terminal is not actually moving at high speed. Problem arises. By using the method disclosed in the first embodiment as the moving state detection method of the mobile terminal, the effect of solving these problems can be obtained.

Embodiment 3 FIG.
A problem to be solved in the third embodiment will be described. When the mobile terminal is located near a cell boundary (also referred to as a cell edge), reselection between the same cells is repeated due to a slight movement of the mobile terminal or a minute change in the wireless environment. This repeated phenomenon of reselection between the same cells may be referred to as a “ping-pong phenomenon”. This will be described with reference to FIG. As shown in (a), the mobile terminal 2603 is located near the cell boundary between the base station 2601 and the base station 2602. (B) shows a conceptual diagram of the received signal interference wave ratio (SIR) between the base station 2601 (thick broken line) and the base station 2602 (thick solid line) in the mobile terminal. Consider a case where the mobile terminal 2603 moves slightly between the points A and B. At point A, the base station 2601 has a higher SIR than the base station 2602, that is, the reception quality is good. Therefore, it is considered that the serving base station of the mobile terminal 2603 becomes the base station 2601 at the point A. At point B, the base station 2602 has a higher SIR than the base station 2601, that is, the reception quality is good. Therefore, it is considered that the serving base station of the mobile terminal 2603 becomes the base station 2602 at the point B. As described above, when the mobile terminal 2603 moves slightly between the points A and B, it is considered that cell reselection or handover is repeated. If cell reselection is repeated, the number of times that the mobile terminal receives broadcast information of a new cell is required to be increased by the increase in cell reselection, resulting in a problem of increased power consumption of the mobile terminal. If the handover is repeated, the control signal between the base station and the mobile terminal increases, and there are problems of effective use of radio resources, an increase of control delay as a mobile communication system, and an increase of power consumption of the mobile terminal. Arise.

A solution in the third embodiment will be described below. If a ping-pong phenomenon or a repeated handover phenomenon between the same cells is detected, the mobile communication system is difficult to perform cell reselection and handover. A specific example will be described below using the LTE system. A specific example of a method for detecting the ping-pong phenomenon is shown below.
(1) The mobile terminal counts the number of consecutive reselections between the same cells. It is assumed that a ping-pong phenomenon is detected when the number of consecutive reselections exceeds a threshold value (threshold value_ping-pong phenomenon) (may be equal to or greater than the threshold value). The number of handovers of the same cell may be counted.
(2) The mobile terminal counts the number of cell reselections between the same cells within a specified time. Suppose that the ping-pong phenomenon is detected when the number of cell reselections of the same cell exceeds the specified value (specified value_ping-pong phenomenon) within the specified time (specified time_ping-pong phenomenon) (may be more than the specified value). . The number of handovers of the same cell may be counted.
The parameters for detecting the ping-pong phenomenon (threshold value_ping-pong phenomenon, specified time_ping-pong phenomenon, specified value_ping-pong phenomenon, etc.) used in the above (1) and (2) are notified from the network side to the mobile terminal. The notification method may be mapped to MIB, SIB, SIB1, SIB2, and SIB3 in the same manner as the switching information of the first modification of the first embodiment. Detailed description is omitted. Moreover, you may notify with a mobility state parameter. Thereby, the mobile terminal can receive the parameter regarding movement together. Thereby, the effect of avoiding the complexity of the mobile communication system and preventing the control delay can be obtained. The ping-pong phenomenon detection parameter may be static. As a result, notification from the network side to the mobile terminal becomes unnecessary, and the effect of effective use of radio resources can be obtained.

  A specific example of a mobile communication system in which cell reselection and handover are difficult is shown below. (1) A parameter for determining whether or not the mobile terminal starts measurement for cell reselection (for example, S_intrasearch) is newly provided for ping-pong phenomenon (for example, S_intrasearch_ping-pong phenomenon) separately from the normal case. . Also, a new scaling factor (for example, Scaling factor for S_intrasearch for ping-pong phenomenon) to be multiplied when a mobile terminal detects a ping-pong phenomenon for determining whether to start measurement for cell reselection (for example, S_intrasearch) Provided. As a specific operation example, when a ping-pong phenomenon is detected, a parameter for determining whether or not the mobile terminal starts measurement for cell reselection is set lower than in a normal case. That is, the S_intrasearch_ping-pong phenomenon is set lower than S_intrasearch, or the Scaling factor for S_intrasearch for ping-pong phenomenon is set to a positive value smaller than 1 so that S_intrasearch becomes a small value. As a result, when the ping-pong phenomenon is detected than in the normal state, measurement for cell reselection is not started until the reception level (reception quality or SIR may be sufficient) of the serving cell is lowered. Thereby, it is possible to realize a mobile communication system in which cell reselection is difficult.

  (2) A parameter (for example, T_reselection) for determining whether or not the mobile terminal performs cell reselection is newly provided for the ping-pong phenomenon (for example, T_reselection_ping-pong phenomenon) separately from the normal case. In addition, a scaling factor (for example, Scaling factor for T_reselection for ping-pong phenomenon) to be multiplied when a ping-pong phenomenon is detected in a parameter (for example, T_reselection) for determining whether or not the mobile terminal performs cell reselection is newly provided. As a specific operation example, when the ping-pong phenomenon is detected, a parameter for determining whether or not the mobile terminal performs cell reselection is set longer than in a normal case. That is, the T_reselection_ping-pong phenomenon is set longer than T_reselection, or the scaling factor for S_intrasearch for ping-pong phenomenon is set to a positive value larger than 1 so that T_reselection becomes a large value. As a result, when the ping-pong phenomenon is detected than in the normal state, cell reselection is not performed unless a new cell (reselection destination) is ranked better (or higher) than the serving cell for a long period of time. It becomes. Thereby, it is possible to realize a mobile communication system in which cell reselection is difficult.

  (3) A cell ranking parameter (for example, the serving cell measurement value adjustment parameter is Q_Hyst) used when the mobile terminal ranks cells is used for a ping-pong phenomenon (for example, Q_Hyst_ping-pong phenomenon) separately from the normal case. Newly provided. Further, a scaling factor (for example, Scaling factor for Q_Hyst for ping-pong phenomenon) to be multiplied when a ping-pong phenomenon is detected is provided for a cell ranking parameter (for example, Q_Hyst) used when the mobile terminal performs cell ranking. As a specific example of operation, when a ping-pong phenomenon is detected, a measurement value adjustment parameter for a serving cell, which is a cell ranking parameter used when performing cell ranking, is set larger than in a normal case. That is, the Q_Hyst_ping-pong phenomenon is set larger than Q_Hyst, or the scaling factor for Q_Hyst for ping-pong phenomenon is set to a positive value larger than 1 so that Q_Hyst becomes a large value. As a result, when the ping-pong phenomenon is detected than in the normal state, neighboring cells are ranked better (or higher) than the serving cell until the serving cell reception level (reception quality or SIR) may be lowered. Disappear. Thereby, it is possible to realize a mobile communication system in which cell reselection is difficult.

  When the ping-pong phenomenon shown above is detected, the parameters for the ping-pong phenomenon to realize a mobile communication system in which cell selection is difficult (for example, S_intrasearch_ping-pong phenomenon, Scaling factor for S_intrasearch for ping-pong phenomenon, T_reselection_ping-pong phenomenon, Scaling factor for T_reselection for ping-pong phenomenon, Q_Hyst _ ping-pong phenomenon, Scaling factor for Q_Hyst for ping-pong phenomenon) is the same as the switching information in the first modification of the first embodiment, as in MIB, SIB, SIB1, SIB2, and SIB3. May be mapped. Detailed description is omitted. When a new S_intrasearch_ping-pong phenomenon is added, it is notified in the same manner as S_intrasearch. When a new T_reselection_ping-pong phenomenon is added, notification is made in the same manner as T_reselection. When adding a new Q_Hyst_Ping-Pong phenomenon, it is notified in the same way as Q_Hyst. When a new scaling factor for the ping-pong phenomenon is added, notification is made in the same manner as the scaling factor for the moving state. Thereby, the parameter used similarly can be received together. Thereby, the effect of avoiding the complexity of the mobile communication system and preventing the control delay can be obtained.

  FIG. 27 shows an example of the operation. In FIG. 27, the steps having the same numbers as those in FIG. 15 perform the same or corresponding processes, and the description of the portions having the same step numbers is omitted. The LTE system will be described as a specific example. The detection method of the ping-pong phenomenon will be described using, for example, (2) a method in which the mobile terminal counts the number of cell reselections of the same cell within a specified time. For example, (3) a ping-pong for a cell ranking parameter (for example, a serving cell measurement value adjustment parameter is Q_Hyst) used when a mobile terminal ranks cells is selected. A description will be given using a method of newly providing a scaling factor (for example, Scaling factor for Q_Hyst for ping-pong phenomenon) to be multiplied when a phenomenon is detected. In step ST2701, the serving cell notifies the mobile terminal being served thereof of the parameters for detecting the ping-pong phenomenon. In Step ST2702, the mobile terminal receives ping-pong phenomenon detection parameters from the serving cell. The mobile terminal starts a timer for a specified time_ping-pong phenomenon. Specified time_Ping-pong timer restarts when it times out. In step ST2703, the serving cell notifies the mobile terminal being served thereby of the parameters for the ping-pong phenomenon. In Step ST2704, the mobile terminal receives a ping-pong phenomenon parameter from the serving cell. In step ST2705, the mobile terminal determines whether a ping-pong phenomenon has been detected. As a specific example of the determination, the count value for detecting the ping-pong phenomenon is larger than the prescribed value_ping-pong phenomenon in the ping-pong phenomenon detecting parameter received in step ST2701 (may be more than the prescribed value_ping-pong phenomenon). )to decide. If larger than the specified value_ping-pong phenomenon, it is determined that the ping-pong phenomenon has been detected, and the process proceeds to step ST2706. If it is equal to or less than the specified value_ping-pong phenomenon, it is determined that no ping-pong phenomenon is detected, and the process proceeds to step ST1511. In step ST2706, the mobile terminal detects the ping-pong phenomenon.

  In step ST2707, the mobile terminal performs adjustment so that it is difficult to reselect a cell. As a specific example of the adjustment, the measurement value adjustment parameter (Q_Hyst) of the serving cell, which is a cell ranking parameter, is multiplied by the Scaling factor for Q_Hyst for ping-pong phenomenon in the ping-pong phenomenon parameter received in step ST2703. Let Q_Hyst 'be the result of multiplication. Scaling factor for Q_Hyst for A positive value greater than 1 is assumed for the ping-pong phenomenon. In step ST2707, the measurement value adjustment parameter (Q_Hyst) of the serving cell used for cell ranking is adjusted to a value larger than normal. That is, Q_Hyst <Q_Hyst ′. It will be described with reference to FIG. 28 that it becomes difficult to reselect a cell by this adjustment. In FIG. 28, the same numbers as those in FIG. In FIG. 28B, the received signal interference wave ratio (SIR) of the base station 2601 is indicated by a thick broken line. The state obtained by adding the measurement value adjustment parameter (Q_Hyst) of the serving cell to the SIR value is a thick dashed line. Further, a state where Q_Hyst ′ is added to the SIR value is a thick two-dot chain line. When this embodiment is not used, base station 2602 has a higher SIR than base station 2601 at point B, that is, reception quality is better. Therefore, it is considered that the serving base station of the mobile terminal 2603 becomes the base station 2602 at the point B. On the other hand, when this embodiment is used, the base station 2602 does not have a higher SIR than the base station 2601 unless the mobile terminal 2601 moves to the point C. That is, cell reselection does not occur unless mobile terminal 2601 moves to point C.

  In Step ST2708, the mobile terminal determines whether cell reselection has been performed. If cell reselection is not performed, the process returns to step ST1501. When cell reselection is performed, the mobile terminal makes a transition to step ST2709. In Step ST2709, the mobile terminal determines whether reselection between the same cells. In the case of reselection between the same cells, the mobile terminal makes a transition to step ST2710. When it is not reselection between the same cells, it returns to step ST1501. In step ST2710, the mobile terminal adds 1 to the count value for detecting the ping-pong phenomenon in order to count the number of cell reselections between the same cells. Thereafter, the process returns to step ST1501. The count value is used for ping-pong detection. Thus, for example, the count value is reset (returned to “0”) when the specified time_ping-pong phenomenon times out. The operation in the case of cell selection and the operation in the case of determining the handover destination on the mobile terminal side are the same as or equivalent to those in FIG.

  The following effects can be obtained by this embodiment. When a ping-pong phenomenon is detected, a mobile communication system in which cell reselection and handover are difficult can be achieved. As a result, even if a mobile terminal located in the vicinity of the cell boundary moves minutely or changes in the wireless environment, cell reselection or handover can be prevented. This will be specifically described with reference to FIG. Even when the mobile terminal 2603 repeats minute movements between the points A and B, when the present embodiment is used, for example, the measurement value adjustment parameter of the serving cell 2601 is adjusted in the direction of increasing. Therefore (for example, the adjusted serving cell measurement value adjustment parameter Q_Hyst ′) also at the point B, the base station 2601 becomes a serving cell, that is, is considered to be within the coverage, that is, the base station 2601 is considered to be higher in the cell ranking than the base station 2602. No reselection is done. Thus, by using the third embodiment, it becomes possible to prevent repeated reselection of cells, and the effect of reducing power consumption of the mobile terminal can be obtained. In addition, it is possible to prevent repeated handovers, and it is possible to obtain effects such as effective utilization of radio resources, reduction of control delay as a mobile communication system, and reduction of power consumption of a mobile terminal.

  Next, a first modification according to the above embodiment will be described. A problem to be solved by this modification will be described. Consider a case where a large number of HeNBs (which may be HNBs) are installed. This will be described with reference to FIG. A mobile terminal 2904 is located near a cell boundary between the base station 2901, the base station 2902, and the base station 2903. Consider a case where the mobile terminal 2904 has moved slightly as indicated by an arrow. In this case, cell reselection or handover with the base station 2902, the base station 2903, and the base station 2901 occurs. Similarly, it is considered that cell reselection also occurs when a minute change in the wireless environment occurs. If cell reselection is repeated, the number of times that the mobile terminal receives broadcast information of a new cell is required to be increased by the increase in cell reselection, resulting in a problem of increased power consumption of the mobile terminal. If the handover is repeated, the control signal between the base station and the mobile terminal increases, and there are problems of effective use of radio resources, an increase of control delay as a mobile communication system, and an increase of power consumption of the mobile terminal. Arise. Since it is not reselection between the same cells or handover, the ping-pong phenomenon is not detected, and the method of Embodiment 3 does not solve the above problem.

The solution in the first modification is shown below. When a reselection repetition phenomenon between CSGs or a handover repetition phenomenon between HeNBs is detected, the mobile communication system is difficult to perform cell reselection and handover. A specific example will be described below using the LTE system. A specific example of a method for detecting a reselection repetition phenomenon between CSGs is shown below. The mobile terminal counts movement between CSG cells (may be movement between HeNBs).
(1) The mobile terminal counts the number of continuous reselections between CSG cells. It is assumed that a reselection repetition phenomenon between CSGs is detected when the number of consecutive reselections exceeds a threshold (reselection repetition phenomenon between threshold_CSG) (may be equal to or greater than the threshold). The number of continuous reselections of the HeNB may be counted. The number of continuous reselections of cells with a small radius may be counted. The number of handovers may be counted instead of the number of reselections.
(2) The mobile terminal counts the number of cell reselections between CSG cells of a specified type within a specified time. The cell reselection count of cells of the specified type (reselection repetition phenomenon between specified type_CSG) within the specified time (reselection repetition phenomenon between specified time_CSG) is the specified value (reselection repetition between specified value_CSG) If it exceeds the threshold (may be greater than the specified value), it is assumed that a reselection phenomenon between CSGs is detected. The number of HeNB reselections may be counted. You may count the reselection frequency of a cell with a small radius. The number of handovers may be counted instead of the number of reselections.
Reselection repetitive phenomenon detection parameter between CSG used in (1) and (2) above (reselection repetitive phenomenon between threshold_CSG, specified time_reselection repetitive phenomenon between CSG, reselection between specified types_CSG The repetitive phenomenon, reselection repetitive phenomenon between specified value_CSG, etc.) are notified from the network side to the mobile terminal. The notification method may be mapped to MIB, SIB, SIB1, SIB2, SIB3, and SIB9 in the same manner as the switching information of the first modification of the first embodiment. Detailed description is omitted. Moreover, you may notify with a mobility state parameter. Thereby, the mobile terminal can receive the parameter regarding movement together. Thereby, the effect of avoiding the complexity of the mobile communication system and preventing the control delay can be obtained. In addition, the reselection repetition phenomenon detection parameter between CSGs may be static. As a result, notification from the network side to the mobile terminal becomes unnecessary, and the effect of effective use of radio resources can be obtained.

A specific example of a mobile communication system in which cell reselection and handover are difficult is shown below.
(1) A parameter for determining whether or not the mobile terminal starts measurement for cell reselection (for example, S_intrasearch) is for reselection repetition phenomenon between CSGs (for example, between S_intrasearch_CSG) separately from the normal case Newly provided for reselection repetition phenomenon). In addition, a scaling factor (for example, Scaling factor for S_intrasearch for) is determined when a reselection repetition phenomenon between CSGs is detected in a parameter (for example, S_intrasearch) for determining whether the mobile terminal starts measurement for cell reselection. New re-selection phenomenon between CSGs). As a specific operation example, when a reselection repetition phenomenon between CSGs is detected, a parameter for determining whether or not the mobile terminal starts measurement for cell reselection is set lower than in a normal case. To do. That is, the reselection repetition phenomenon between S_intrasearch_CSGs is set lower than S_intrasearch, or the reselection repetition phenomenon between Scaling factor for S_intrasearch for CSGs is set to a positive value smaller than 1, and S_intrasearch is set to a small value. As a result, when the reselection repetition phenomenon between CSGs is detected as compared with the normal state, measurement for cell reselection is not started until the reception level (reception quality or SIR may be sufficient) of the serving cell is lowered. It will be. Thereby, it is possible to realize a mobile communication system in which cell reselection is difficult.

  (2) A parameter for determining whether or not the mobile terminal performs cell reselection (for example, T_reselection) is for reselection repetition phenomenon between CSGs separately from the normal case (for example, reselection repetition phenomenon between T_reselection_CSG) Newly provided. In addition, a scaling factor (for example, Scaling factor for T_reselection for CSG) that is multiplied when a reselection repetition phenomenon between CSGs is detected in a parameter (for example, T_reselection) for determining whether or not the mobile terminal performs cell reselection. Phenomenon). As a specific operation example, when a reselection repetition phenomenon between CSGs is detected, a parameter for determining whether or not the mobile terminal performs cell reselection is set longer than in a normal case. That is, the reselection repetition phenomenon between T_reselection_CSGs is set longer than T_reselection, or the reselection repetition phenomenon between Scaling factor for S_intrasearch for CSG is set to a positive value larger than 1 so that T_reselection becomes a large value. As a result, if a reselection repetition phenomenon between CSGs is detected than in the normal state, if a new cell (reselection destination) is not ranked better (or higher) than the serving cell for a long period, cell reselection Will not be performed. Thereby, it is possible to realize a mobile communication system in which cell reselection is difficult.

  (3) A cell ranking parameter (for example, the serving cell measurement value adjustment parameter is Q_Hyst) used when the mobile terminal ranks cells is used for reselection repetition phenomenon between CSGs (for example, Q_Hyst). _ New repetitive phenomenon between CSG). In addition, a scaling factor (for example, a scaling factor for Q_Hyst for CSG) multiplied by a cell selection parameter (for example, Q_Hyst) used when the mobile terminal performs cell ranking is detected when a reselection repetition phenomenon between CSGs is detected. New selection repetition phenomenon). As a specific operation example, when the reselection repetition phenomenon between CSGs is detected, the measurement adjustment parameter of the serving cell of the cell ranking parameter used when performing cell ranking is set to be large compared to the normal case. To do. That is, the reselection repetition phenomenon between Q_Hyst_CSG is set larger than Q_Hyst, or the reselection repetition phenomenon between Scaling factor for Q_Hyst for CSG is set to a positive value larger than 1 so that Q_Hyst becomes a large value. Accordingly, when the reselection repetition phenomenon between CSGs is detected than in the normal state, the neighboring cell is better than the serving cell until the reception level of the serving cell (reception quality or SIR may be sufficient) (or No higher ranking). Thereby, it is possible to realize a mobile communication system in which cell reselection is difficult.

  Parameters for reselection repetition phenomenon between CSG (for example, reselection repetition phenomenon between S_intrasearch_ CSG) to realize a mobile communication system in which cell selection is difficult when the reselection repetition phenomenon between CSGs shown above is detected , Scaling factor for S_intrasearch for CSG reselection repetition phenomenon, T_reselection_ CSG reselection repetition phenomenon, Scaling factor for T_reselection for CSG reselection repetition phenomenon, Q_Hyst _ CSG reselection repetition phenomenon, Scaling factor for Q_Hyst The notification method of the reselection repetition phenomenon between for CSGs) may be mapped to MIB, SIB, SIB1, SIB2, and SIB3 in the same manner as the switching information of the first modification of the first embodiment. Detailed description is omitted. When adding a new reselection phenomenon between S_intrasearch_CSGs, it is notified in the same way as S_intrasearch. When a new reselection phenomenon between T_reselection_CSGs is newly added, notification is made in the same manner as T_reselection. When a new reselection phenomenon between Q_Hyst_CSG is added, it is notified in the same way as Q_Hyst. When a scaling factor for reselection repetition phenomenon between CSGs is newly added, notification is made in the same manner as the scaling factor for the moving state. Thereby, the parameter used similarly can be received together. Thereby, the effect of avoiding the complexity of the mobile communication system and preventing the control delay can be obtained. In addition, when a reselection repetition phenomenon between CSGs is detected, a parameter for reselection repetition phenomenon between CSGs for realizing a mobile communication system in which cell selection is difficult is not provided, and a ping-pong phenomenon is detected. The parameters for the ping-pong phenomenon for realizing a mobile communication system in which cell selection is difficult may be shared. Thereby, the amount of information notified from the serving cell to the mobile terminal can be reduced, and the effect of effective use of radio resources can be obtained. In addition, the effects of avoiding complexity of the mobile communication system and preventing control delay can be obtained.

  FIG. 30 shows an example of the operation. In FIG. 30, steps having the same numbers as those in FIG. 15 perform the same or corresponding processes, and thus description of the portions having the same step numbers is omitted. The LTE system will be described as a specific example. A method for detecting a reselection repetition phenomenon between CSGs will be described using, for example, (2) a method of counting the number of cell reselections of a specified type of CSG cell within a specified time. A method for realizing a mobile communication system in which cell reselection is difficult is, for example, (3) CSG for cell ranking parameters (for example, the serving cell measurement value adjustment parameter is Q_Hyst) used when the mobile terminal ranks cells. A description will be given using a method of newly providing a scaling factor (for example, a reselection repetition phenomenon between Scaling factor for Q_Hyst for CSG) to be multiplied when a reselection repetition phenomenon is detected.

  In step ST3001, the serving cell notifies the subordinate mobile terminal of the reselection repetition phenomenon detection parameter between the CSGs. In Step ST3002, the mobile terminal receives a reselection repetition phenomenon detection parameter between CSGs from the serving cell. The mobile terminal starts a timer for the reselection repetition phenomenon during the specified time_CSG. The timer of the reselection repetition phenomenon during the specified time_CSG is restarted when it times out. In step ST3003, the serving cell notifies the parameters for the reselection repetition phenomenon between CSGs to the mobile terminals being served thereby. In Step ST3004, the mobile terminal receives parameters for reselection repetition phenomenon between CSGs from the serving cell. In step ST3005, the mobile terminal determines whether a reselection repetition phenomenon between CSGs has been detected. As a specific example of the determination, the count value for detecting the reselection repetition phenomenon between CSGs is based on the reselection repetition phenomenon between the specified values_CSG in the reselection repetition phenomenon detection parameter between CSGs received in step ST3001. It is determined whether it is larger (may be more than the reselection phenomenon between the specified value_CSG).

  The count value counts the number of reselections for CSG cells of a specified type (reselection repeat phenomenon between specified types_CSG) in the parameter for detecting reselection repeat phenomenon between CSGs received in step ST3001. A specific example will be described with reference to FIG. For example, if there are three types, the reselection with the base station 2902, the base station 2903, and the base station 2901 is repeated, and the reselection for the three types of CSG cells is counted. Reselection to other base stations during the reselection recurring phenomenon is not counted. When the count value is larger than the reselection repetition phenomenon between the prescribed values_CSG, it is determined that the reselection repetition phenomenon between CSGs has been detected, and the process proceeds to step ST3006. If the count value is equal to or smaller than the reselection repetition phenomenon between the prescribed values_CSG, it is determined that the reselection repetition phenomenon between CSGs is not detected, and the process proceeds to step ST1511. In Step ST3006, the mobile terminal detects a reselection repetition phenomenon between CSGs.

  In step ST3007, the mobile terminal performs adjustment so that cell reselection is difficult. As a specific example of the adjustment, the serving cell measurement parameter adjustment parameter (Scaling factor for Q_Hyst for CSG reselection repetition phenomenon in the reselection repetition phenomenon parameter between CSGs received in step ST3003) Q_Hyst). Let Q_Hyst 'be the result of multiplication. A positive value greater than 1 is assumed for the reselection repetition phenomenon between Scaling factor for Q_Hyst for CSG. In step ST3007, the measurement value adjustment parameter (Q_Hyst) of the serving cell used for cell ranking is adjusted to a larger value than usual. In step ST3008, the mobile terminal determines whether cell reselection has been performed. If cell reselection is not performed, the process returns to step ST1501. When cell reselection is performed, the mobile terminal makes a transition to step ST3009. In step ST3009, the mobile terminal determines whether or not the reselection is for a CSG cell of a specified type (reselection repetition phenomenon between specified type_CSG). In the case of reselection to the cell, the mobile terminal makes a transition to step ST3010. When it is not reselection with respect to a regular type CSG cell, it returns to step ST1501. In Step ST3010, the mobile terminal adds 1 to the count value for detecting the reselection repetitive phenomenon between CSGs in order to count the number of reselections for the specified type of CSG cell. Thereafter, the process returns to step ST1501. The count value is used for reselection phenomenon detection between CSGs. Thus, for example, the count value is reset (returned to “0”) when the reselection repetition phenomenon during the specified time_CSG times out. Since the operation in the case of cell selection and the operation in the case of determining the handover destination on the mobile terminal side are the same as or equivalent to those in FIG. 30, description thereof will be omitted.

  The following effects can be obtained by this modification. When a reselection repetition phenomenon between CSGs is detected, a mobile communication system in which cell reselection and handover are difficult can be achieved. As a result, even if a mobile terminal located in the vicinity of the cell boundary moves minutely or changes in the wireless environment, cell reselection or handover can be prevented. By using the first modification in this way, it becomes possible to prevent repeated cell reselection at a location where a large number of HeNBs (or HNBs) are installed, thereby reducing power consumption of the mobile terminal. The effect that can be obtained. In addition, it is possible to prevent repeated handovers, and it is possible to obtain effects such as effective utilization of radio resources, reduction of control delay as a mobile communication system, and reduction of power consumption of a mobile terminal.

  Parameters for ping-pong phenomenon disclosed in the third embodiment (for example, S_intrasearch_ ping-pong phenomenon, Scaling factor for S_intrasearch for ping-pong phenomenon, T_reselection_ ping-pong phenomenon, Scaling factor for T_reselection for ping-pong phenomenon, Q_Hyst _ ping-pong phenomenon, Scaling factor for Q_Hyst for ping-pong phenomenon) or parameters for reselection repetition phenomenon between CSGs disclosed in the first modification of the third embodiment (for example, reselection repetition phenomenon between S_intrasearch_CSG, reselection repetition between Scaling factor for S_intrasearch for CSG) Phenomenon, reselection repetition phenomenon between T_reselection_ CSG, reselection repetition phenomenon between Scaling factor for T_reselection for CSG, reselection repetition phenomenon between Q_Hyst _ CSG, and reselection repetition phenomenon between Scaling factor for Q_Hyst for CSG) Limit values to a certain range Is good. These parameters make cell reselection from the serving cell difficult. Therefore, if the range that these parameters can take is not limited, the mobile terminal cannot reselect other cells because cell reselection will not be performed no matter how much the reception status from the serving cell deteriorates. In addition, reception from the serving cell becomes impossible. In order to solve this problem, the possible range of the parameters is limited. It is good to limit within the range which can receive from a serving cell.

  For example, for the S_intrasearch_ping-pong phenomenon, a minimum value that enables reception from the serving cell is provided (for example, S_intrasearch_min), and the setting value of the S_intrasearch_ping-pong phenomenon is set to S_intrasearch_ping-pong phenomenon ≧ S_intrasearch_min. Also, for example, for the Scaling factor for S_intrasearch for ping-pong phenomenon, a minimum value that allows reception from the serving cell is set (for example, Scaling factor for S_intrasearch for min), and the setting value of Scaling factor for S_intrasearch for ping-pong phenomenon is set. , Scaling factor for S_intrasearch for ping-pong phenomenon ≧ Scaling factor for S_intrasearch for min. The same applies to the other parameters. The values necessary for the limitation may be determined in advance or may be notified from the network to the mobile terminal. The notification method from the network to the mobile terminal may be mapped to MIB, SIB, SIB1, SIB2, and SIB3 in the same manner as the switching information of the first modification of the first embodiment. Detailed description is omitted. In this way, when the ping-pong phenomenon occurs, in addition to the effect described in the first to third modifications by making it difficult to reselect a cell, before the mobile terminal can no longer receive from the serving cell. In addition, it is possible to obtain the effect that the cell can be reselected.

  The period for using the parameter may be until a new parameter is notified from the network, or a timer for indicating the period for using the parameter may be provided. The timer value may be determined in advance or may be notified from the network to the mobile terminal. The notification method from the network to the mobile terminal may be mapped to MIB, SIB, SIB1, SIB2, and SIB3 in the same manner as the switching information of the first modification of the first embodiment. Detailed description is omitted. This makes it possible to flexibly perform cell reselection according to the situation at that time even when the state of the mobile terminal changes with time.

  Next, a second modification according to the above embodiment will be described. In the present modification, another solution is disclosed for the same problem as in the third embodiment and the first modification of the third embodiment. The solution in this modification is shown below. Either or both of the information of the ping-pong phenomenon of the mobile terminal and the information of the reselection repetition phenomenon between CSGs are notified to the network side (base station), and the base station limits the measurement target cells. A specific example will be described below using the LTE system. Specific examples of information on the ping-pong phenomenon and information on the reselection repetition phenomenon between CSGs are shown below. The presence / absence of ping-pong phenomenon detection and the presence / absence of reselection repetition phenomenon detection between CSGs may be notified from the mobile terminal to the base station. Specific examples of the method for detecting the ping-pong phenomenon and the method for detecting the reselection repetition phenomenon between CSGs are the same as those in the third embodiment and the first modification example, and thus the description thereof is omitted. The method of notifying the mobile state information from the mobile terminal to the base station (serving cell) can be the same method as the mobile state information of the fifth modification of the second embodiment. Therefore, detailed description is omitted. The specific example of the timing of notifying the ping-pong phenomenon information and the reselection repetition phenomenon information between CSGs from the mobile terminal to the base station (serving cell) is the same as the movement state information of the fifth modification of the second embodiment. Method can be used. Therefore, detailed description is omitted.

  FIG. 31 shows an example of the operation. The LTE system will be described as a specific example. A mobile terminal notifies a measurement report to a serving cell in step ST3101. In step ST3102, the serving cell receives a measurement report from the mobile terminal. In Step ST3103, the mobile terminal notifies the serving cell of both or one of the information on the ping-pong phenomenon of the mobile terminal and the information on the reselection repetition phenomenon between CSGs. In Step ST3104, the serving cell receives information on the ping-pong phenomenon of the mobile terminal and / or information on the reselection repetition phenomenon between CSGs from the mobile terminal. At that time, a cell causing a ping-pong phenomenon or a cell causing a reselection repetition phenomenon between CSGs may be notified. PCI, GCI, etc. can be considered as cell information. Thereby, it is possible to obtain an effect that a cell causing a ping-pong phenomenon on the network side or a cell causing a reselection repetition phenomenon between CSGs can be specified. In step ST3105, the serving cell changes measurement settings for the mobile terminal. As a specific example of the setting change, based on the information of the cell causing the ping-pong phenomenon received in step ST3104 or the cell causing the reselection repetition phenomenon between CSGs, the cells are transferred to the mobile terminal. Remove from measurement settings. In step ST3106, the serving cell notifies the mobile terminal of the measurement setting. In Step ST3107, the mobile terminal receives the measurement setting from the serving cell. As a result, the mobile terminal does not perform measurement of the cell causing the ping-pong phenomenon or the cell causing the reselection repetition phenomenon between the CSGs.

  The following effects can be obtained by this embodiment. A cell causing a ping-pong phenomenon or a cell causing a reselection repetition phenomenon between CSGs can be deleted from the measurement target of the mobile terminal. Thereby, a cell causing a ping-pong phenomenon or a cell causing a reselection repetition phenomenon between CSGs can be deleted from the handover destination. As a result, it is possible to prevent handover from being performed even when a mobile terminal located in the vicinity of a cell boundary undergoes a minute movement or a minute change in the wireless environment. By using the second modification of the third embodiment, it becomes possible to prevent repeated handovers, and it is possible to effectively use radio resources, reduce control delay as a mobile communication system, and reduce power consumption of a mobile terminal. An effect can be obtained. The second modification example can be used in combination with the third modification example and the first modification example of the third embodiment.

  Although the present invention does not specifically refer to the frequency carrier of the system, cell reselection, cell selection, and handover within the same frequency carrier (intra-frequency) may be performed, and other frequency carriers (inter- frequency) cell reselection, cell selection, and handover. For example, the present invention can be applied to a case where the CSG cell is operated on a dedicated frequency carrier different from that of the non-CSG cell.

  Although the present invention has been described centering on the LTE system (E-UTRAN), the present invention is applicable to W-CDMA systems (UTRAN, UMTS) and LTE-Advanced (LTE-Advanced). Further, a mobile communication system in which a CSG (Closed Subscriber Group) is introduced, a communication system in which an operator identifies a subscriber and access is permitted to the identified subscriber, as in CSG, and HeNB Similarly, the present invention can be applied to a communication system in which a cell having a smaller cell radius than a normal cell is introduced. In LTE advanced and the like, not only base stations (eNB, HNB, HeNB, etc.) but various devices or nodes are considered for transmission / reception and multihop at multiple points. The present invention is also applied to the case where node boundaries increase due to the installation of these various devices or nodes, node changes (node reselection, node handover), and many ping-pong phenomena between nodes occur. It is possible.

Claims (8)

A mobile terminal that transmits and receives data using an OFDM (Orthogonal Frequency Division Multiplexing) scheme as a downlink access scheme and an SC-FDMA (Single Career Frequency Division Multiple Access) scheme as an uplink access scheme, and is located within a predetermined area A first cell forming an area communicable with the mobile terminal, a base provided in each of the second cells forming an area communicable with the mobile terminal within a range narrower than the first cell In a mobile communication system including a station,
The mobile terminal determines movement state information indicating a movement state of the mobile terminal based on the number of times of cell selection performed for a certain period of time, and cell selection notified from the movement state information and the base station When cell selection is performed based on a parameter for controlling the cell, and the selected cell is the first cell, a count is added to the number of cell selections, and the selected cell is In the case of a cell, the mobile communication system is characterized in that no count is added to the number of cell selections. The movement state information includes a high-speed movement state indicating that the mobile terminal is moving at a high speed, a medium-speed movement state indicating that the mobile terminal is moving at a slower speed than the high-speed movement state, and a comparison with the medium-speed movement state. The normal movement state indicating that the mobile terminal is moving at a slow speed, and the cell selection by the mobile terminal is based on the parameter notified from the base station, the medium speed movement in the high speed movement state. 2. The mobile communication system according to claim 1, wherein the mobile communication system is controlled to perform cell selection more easily than in the normal state and the normal movement state. The second cell is a cell for a specific subscriber that is a communication cell permitted to be used by a specific terminal or subscriber, and the mobile terminal determines that the selected cell selected by the cell is the cell for the specific subscriber. The mobile communication system according to claim 1, wherein the determination is made based on an indicator included in broadcast information transmitted from the selected cell. The second cell is a cell for a specific subscriber that is a communication cell permitted to be used by a specific terminal or subscriber, and the mobile terminal determines that the selected cell selected by the cell is the cell for the specific subscriber. , Information for identifying each cell included in a synchronization signal transmitted from a base station that can be received by the mobile terminal, and identifying a cell other than the specific subscriber cell and the specific subscriber cell The mobile communication system according to claim 1, wherein the determination is made based on cell identification information including information to be performed. The mobile terminal performs cell selection and handover to the first cell, and does not perform cell selection and handover to the second cell when the movement state information is a high-speed movement state, and the movement state information is medium-speed movement. The mobile communication system according to any one of claims 2 to 4, wherein cell selection and handover to the first cell and the second cell are performed in a state or a normal movement state. The mobile terminal counts the number of cell selections made between the same cells, and when the number of continuous selections exceeds a predetermined threshold or when the number of cell selections of the same cell exceeds a predetermined threshold within a specified time. The mobile communication system according to any one of claims 2 to 4, wherein cell selection and handover are controlled. A mobile terminal that transmits and receives data using an OFDM (Orthogonal Frequency Division Multiplexing) scheme as a downlink access scheme and an SC-FDMA (Single Career Frequency Division Multiple Access) scheme as an uplink access scheme, and is located within a predetermined area A first cell forming an area communicable with the mobile terminal, a base provided in each of the second cells forming an area communicable with the mobile terminal within a range narrower than the first cell In a mobile communication system including a station,
The mobile terminal determines movement state information indicating a movement state of the mobile terminal based on the number of times of cell selection performed for a certain period of time, and cell selection notified from the movement state information and the base station Cell selection based on a parameter for controlling the cell, and when the movement state information is a high-speed movement state, cell selection or handover to the first cell is performed, and Moving without performing cell selection or handover, and performing cell selection or handover to the first cell and the second cell when the movement state information is a medium speed movement state or a normal movement state Body communication system. A mobile terminal that transmits and receives data using an OFDM (Orthogonal Frequency Division Multiplexing) scheme as a downlink access scheme and an SC-FDMA (Single Career Frequency Division Multiple Access) scheme as an uplink access scheme, and is located within a predetermined area A first cell forming an area communicable with the mobile terminal, a base provided in each of the second cells forming an area communicable with the mobile terminal within a range narrower than the first cell In a mobile communication system including a station,
The mobile terminal determines movement state information indicating a movement state of the mobile terminal based on the number of times of cell selection performed for a certain period of time, and cell selection notified from the movement state information and the base station Cell selection is performed based on a parameter for controlling the cell count, and the number of cell selections between the same cells is counted. If the number of continuous selections exceeds a predetermined threshold or within the specified time, A mobile communication system, wherein cell selection or handover is controlled when the number of cell selections exceeds a predetermined threshold.

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