JP2009290911A - Cell selection method, and mobile station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suitably select a standby cell in an environment wherein a CSG cell and a macrocell are both present. <P>SOLUTION: A cell selection method includes a step A of judging whether a first CSG cell satisfies prescribed conditions when a mobile station UE uses a first macrocell as a standby cell and a step B of changing the standby cell from the first macrocell to the first CSG cell when the mobile station UE determines that the first CSG cell satisfies the prescribed conditions. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cell selection method in which a mobile station selects a standby cell from a specific cell that can be selected only as a specific mobile station as a standby cell, and a general cell in which all mobile stations can be selected as standby cells, and a mobile station About.

  In 3GPP (3rd Generation Partnership Project) RAN-WG, a home base station HNB using “LTE (Long Term Evolution)” as a radio access scheme is discussed.

  Specifically, according to the current 3GPP regulations, in a mobile communication system, a specific mobile station belonging to a CSG (Closed Subscriber Group) under the home base station HNB (a mobile station that is allowed to select a specific cell as a standby cell) ) Is configured to manage.

  That is, according to the current 3GPP regulations, only a specific mobile station belonging to the CSG can perform communication via a CSG cell (specific cell) under the home base station HNB.

3GPP TS36.331 3GPP TS25.331 3GPP TS36.300

  However, the current 3GPP rules do not specify how a mobile station selects a standby cell in an environment in which CSG cells and macro cells are mixed.

  Therefore, even when a mobile station having a macro cell as a standby cell is located in an area where a CSG cell having the mobile station as a specific mobile station can be selected as a standby cell, this can be detected. There is a possibility that the standby cell cannot be changed to the CSG cell.

  Accordingly, the present invention has been made in view of the above-described problems, and provides a cell selection method and a mobile station that can appropriately select a standby cell in an environment in which CSG cells and macro cells are mixed. With the goal.

  The first feature of the present invention is that a mobile station selects a standby cell from a specific cell that can be selected only as a standby cell by a specific mobile station and a general cell that can be selected as a standby cell by all mobile stations. In the selection method, when the mobile station uses the first general cell as a standby cell, a step A for determining whether or not a predetermined condition is satisfied, and the mobile station satisfies the predetermined condition. And a step B of changing the standby cell from the first general cell to the first specific cell.

  In the first aspect of the present invention, in the step A, the mobile station has at least a first specific cell in which the first general cell is a standby cell and the mobile station is the specific mobile station. When it is determined that it is located in a general cell that is partially overlapped, it may be determined whether or not the predetermined condition is satisfied.

  In the first aspect of the present invention, a first frequency used in the first specific cell is different from a second frequency used in the first general cell, and in the step A, the mobile station The predetermined condition is satisfied when it is determined that the radio quality in one specific cell is the best among the cells using the first frequency and the radio quality in the first specific cell satisfies the first radio quality. In step B, the standby cell may be changed from the first general cell to the first specific cell.

  In the first aspect of the present invention, a first frequency used in the first specific cell is different from a second frequency used in the first general cell, and in the step A, the mobile station It is determined that the difference between the radio quality in one specific cell and the best radio quality in the cell using the first frequency is within a predetermined offset, and the radio quality in the first specific cell satisfies the first radio quality. In this case, it may be determined that the predetermined condition is satisfied, and the standby cell may be changed from the first general cell to the first specific cell in the step B.

  In the first aspect of the present invention, in the step A, when the mobile station determines that the radio quality in the first specific cell satisfies the first radio quality, the mobile station determines that the predetermined condition is satisfied. In the step B, the standby cell may be changed from the first general cell to the first specific cell.

  In the first feature of the present invention, when the mobile station becomes unable to detect a general cell that satisfies the second radio quality, and the third radio quality that does not make the mobile station the specific mobile station, When the second specific cell to be satisfied is detected, the process C may be set as a standby cell.

  In the first aspect of the present invention, when the mobile station uses the second specific cell as a standby cell and detects a second general cell that satisfies the second radio quality, the mobile station determines the standby cell as the first cell. You may have the process of changing from 2 specific cells to this 2nd general cell.

  The second feature of the present invention is configured to select a standby cell from a specific cell that can be selected only as a standby cell by a specific mobile station and a general cell that can be selected as a standby cell by all mobile stations. If the first general cell is the standby cell, the mobile station determines whether or not the predetermined condition is satisfied, and if it is determined that the predetermined condition is satisfied, the standby cell is The gist is to include a cell selection unit configured to change from one general cell to the first specific cell.

  In the second aspect of the present invention, the cell selection unit is a case where the first general cell is a standby cell, and is at least partially superimposed on a first specific cell having the mobile station as the specific mobile station. If it is determined that the cell is located in the general cell, it may be configured to determine whether or not the predetermined condition is satisfied.

  In the second aspect of the present invention, the first frequency used in the first specific cell is configured to be different from the second frequency used in the first general cell, and the cell selection unit includes: When the radio quality in the first specific cell is the best among the cells using the first frequency and the radio quality in the first specific cell is determined to satisfy the first radio quality, the predetermined condition is The standby cell may be determined to be satisfied and changed from the first general cell to the first specific cell.

  In the second aspect of the present invention, the first frequency used in the first specific cell is configured to be different from the second frequency used in the first general cell, and the cell selection unit includes: When the difference between the radio quality in the first specific cell and the best radio quality in the cell using the first frequency is within a predetermined offset, and the radio quality in the first specific cell satisfies the first radio quality When it is determined, it may be determined that the predetermined condition is satisfied, and the standby cell is changed from the first general cell to the first specific cell.

  In the second aspect of the present invention, when the cell selection unit determines that the radio quality in the first specific cell satisfies the first radio quality, the cell selection unit determines that the predetermined condition is satisfied, and the standby cell May be changed from the first general cell to the first specific cell.

  2nd characteristic of this invention WHEREIN: The said cell selection part is a case where it becomes impossible to detect the general cell which satisfy | fills 2nd radio | wireless quality, and 3rd radio | wireless quality which does not make the said mobile station the said specific mobile station When a second specific cell satisfying the above condition is detected, the second specific cell may be configured as a standby cell.

  In the second aspect of the present invention, when the cell selection unit uses the second specific cell as a standby cell and detects a second general cell that satisfies the second radio quality, the cell selection unit selects the standby cell as the standby cell. It may be configured to change from the second specific cell to the second general cell.

  A third feature of the present invention is that a mobile station selects a standby cell from a first cell using a first frequency and a second cell using a second frequency different from the first frequency. In the selection method, when the priority of the second cell is higher than the priority of the first cell, the mobile station using the first cell as a standby cell has a predetermined radio quality in the second cell. The gist is to have a step of changing the standby cell from the first cell to the second cell when it is determined that the wireless quality is satisfied.

  A fourth feature of the present invention is that a mobile station selects a standby cell from a first cell using a first frequency and a second cell using a second frequency different from the first frequency. In the selection method, when the priority of the second cell is the same as the priority of the first cell, the mobile station that uses the first cell as a standby cell has radio quality in the second cell. The present invention includes a step of changing a standby cell from the first cell to the second cell when it is determined that the predetermined wireless quality is satisfied and the wireless quality of the first cell does not satisfy the predetermined wireless quality. To do.

  A fifth feature of the present invention is that a mobile station selects a standby cell from among a first cell using a first frequency and a second cell using a second frequency different from the first frequency. In the selection method, when the priority of the second cell is lower than the priority of the first cell, the mobile station using the first cell as a standby cell has a predetermined radio quality in the second cell. The gist is to have a step of changing the standby cell from the first cell to the second cell when it is determined that the wireless quality is satisfied and the wireless quality of the first cell does not satisfy the predetermined wireless quality. .

  In the third to fifth aspects of the present invention, when the second cell is a specific cell that can be selected only as a standby cell by the specific mobile station, the mobile station further includes a radio in the second cell. When it is determined that the difference between the quality and the best radio quality in the cell using the second frequency is within a predetermined offset, the standby cell may be changed from the first cell to the second cell.

  A sixth aspect of the present invention is configured to select a standby cell from among a first cell using a first frequency and a second cell using a second frequency different from the first frequency. And the second cell has a higher priority than the first cell when the first cell is a standby cell and the radio quality in the second cell is The gist is to include a cell selection unit configured to change the standby cell from the first cell to the second cell when it is determined that the predetermined radio quality is satisfied.

  A seventh aspect of the present invention is configured to select a standby cell from among a first cell using a first frequency and a second cell using a second frequency different from the first frequency. And the second cell has the same priority as the first cell, and the first cell is a standby cell, and the radio quality in the second cell Is configured to change the standby cell from the first cell to the second cell when it is determined that the wireless quality satisfies the predetermined wireless quality and the wireless quality of the first cell does not satisfy the predetermined wireless quality. The gist is to include a cell selection unit.

  An eighth aspect of the present invention is configured to select a standby cell from among a first cell using a first frequency and a second cell using a second frequency different from the first frequency. And the second cell has a priority lower than that of the first cell, the first cell is a standby cell, and the radio quality in the second cell is A cell configured to change the standby cell from the first cell to the second cell when it is determined that the predetermined wireless quality is satisfied and the wireless quality of the first cell does not satisfy the predetermined wireless quality The gist is to include a selection unit.

  In the sixth to eighth features of the present invention, when the second cell is a specific cell that can be selected as a standby cell only by a specific mobile station, the cell selection unit further includes: It is configured to change the standby cell from the first cell to the second cell when it is determined that the difference between the radio quality and the best radio quality in the cell using the second frequency is within a predetermined offset. It may be.

  As described above, according to the present invention, it is possible to provide a cell selection method and a mobile station that can appropriately select a standby cell in an environment in which CSG cells and macro cells are mixed.

1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. FIG. 3 is a functional block diagram of a mobile station according to the first embodiment of the present invention. It is a figure for demonstrating the operation | movement which determines the standby cell of the mobile station which concerns on the 1st Embodiment of this invention. 4 is a flowchart illustrating an operation of determining a standby cell of the mobile station according to the first embodiment of the present invention. 4 is a flowchart illustrating an operation of determining a standby cell of the mobile station according to the first embodiment of the present invention. 4 is a flowchart illustrating an operation of determining a standby cell of the mobile station according to the first embodiment of the present invention. It is a figure for demonstrating the mobile communication system which concerns on the example 1 of a change of this invention.

(Configuration of mobile communication system according to the first embodiment of the present invention)
The configuration of the mobile communication system according to the first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the mobile communication system according to the present embodiment includes switching base stations MME (Mobility Management Entity) and home base stations HNB # 1 and #NB that manage CSG cells (specific cells) # 1 and # 2, respectively. 2, radio base stations eNB # 1 and # 2 that manage macro cells (general cells) # 1 and # 2, respectively, and a mobile station UE.

  Here, the CSG cell is a cell in which a CSG that is a group having an access right is set, and the macro cell is a cell in which no CSG is set.

  In addition, when the mobile station UE does not belong to the CSG set for the CSG cell, the mobile station UE becomes a “general mobile station” in the CSG cell, and when the mobile station UE belongs to the CSG set for the CSG cell, It becomes a “specific mobile station” in the CSG cell.

  In the mobile communication system according to the present embodiment, the CSG cell # 1 uses the mobile station UE as “a mobile station that allows a specific mobile station (CSG cell # 1 to be a standby cell, ie, communication via CSG cell # 1. The CSG cell # 2 is a cell that does not designate the mobile station UE as a “specific mobile station”. Therefore, when viewed from the mobile station UE, the CSG cell # 1 is the “own CSG cell”, and the CSG cell # 2 is the “other CSG cell”.

  In the example of FIG. 1, CSG cell # 1 is partially overlapped with macro cells # 1 and # 2, and CSG cell # 2 is also partially overlapped with macro cells # 1 and # 2. Yes.

  The CSG can be set not only for cells under a home base station installed in a so-called home but also for cells under a radio base station installed in an office environment, a coffee shop, a school, or the like. For example, it may be assumed that access rights are given only to office employees, or temporary access rights are given to coffee shop employees and visitors.

  In this case, the same CSG may be set over a plurality of cells or a plurality of radio base stations, and the radio base stations vary widely from small and low power to large and high power. It is.

  Therefore, in this specification, these scenarios are included, and for convenience, a radio base station that manages a cell (CSG cell) in which a CSG is set is referred to as a “home base station HNB”.

  The switching apparatus MME is configured to manage a specific mobile station (a mobile station that allows communication via each CSG cell) in each CSG cell under each home base station HNB connected to the switching apparatus MME. .

  The home base station HNB may be configured to manage a specific mobile station in each CSG cell under the home base station HNB, but the home base station HNB is arranged in a location that can be reached by the user. In view of security and the like, it is preferable that the switching apparatus MME is configured to manage a specific mobile station in each CSG cell as described above.

  As shown in FIG. 2, the mobile station UE includes a broadcast information reception unit 11, an individual signal reception unit 12, a parameter storage unit 13, a cell information management unit 14, a search location information management unit 15, and a cell selection unit. 16.

  The broadcast information receiving unit 11 transmits from a radio base station eNB or home base station HNB that manages a standby cell (CSG cell or macro cell) of the mobile station UE via a BCH (Broadcast Channel), SU (Scheduling Unit), or the like. The broadcast information received is configured to be received.

  For example, the broadcast information receiving unit 11 receives information (cell ID and TA-ID) for identifying the cell (or TA: Tracking Area) where the mobile station UE is currently located as the broadcast information. It is configured.

  Also, the broadcast information receiving unit 11 receives, as such broadcast information, information (different frequency information) regarding the frequency of the cell that is at least partially superimposed on the cell (macro cell or CSG cell) where the mobile station UE is currently located. It is configured.

  Here, when the mobile station UE is located in the cell F2 using the frequency f2, the “different frequency information” identifies each of the cells F1, F3, and F4 that are at least partially superimposed on the cell F2. Information (TA-ID and cell ID), frequencies f1, f3, and f4 (for example, xx MHz) used in cells F1, F3, and F4 that are at least partially overlapped with the cell F2, respectively. It is configured.

  The individual signal receiving unit 12 is configured to receive an individual signal transmitted from the exchange apparatus MME.

  For example, the dedicated signal receiving unit 12 is configured such that the mobile station UE has a “own CSG cell list” that is a list of CSG cells in which the CSG to which the mobile station UE belongs is set as the dedicated signal, and the CSG cell It is configured to receive a “superposed macro cell list” that is a list of macro cells that are at least partially superimposed on each.

  Here, when the individual signal receiving unit 12 enters a macro cell (or TA) that is at least partially superimposed on the own CSG cell of the mobile station UE, the individual signal receiving unit 12 described above as the “own CSG cell list” as the individual signal. And “a superimposed macro cell list” or the like may be received.

The parameter storage unit 13 includes parameters “Hysteresis (for example, xxdB)” and “T _reselection (for example, xx seconds) included in the determination information used for determining whether to change the standby cell of the mobile station UE. "," Margin (for example, xxdB) ", and the like.

  Such parameters may have different values for each cell, or may have values common to a plurality of cells. Further, such a parameter may be notified as the above-described notification information or may be notified as the above-described individual signal.

  The cell information management unit 14 is configured to manage information (cell information) related to each cell.

As such cell information, the cell information management unit 14 sets “priority”, threshold value “Q _RSRPmin ” or “Q _RSRQmin ”, “frequency used”, and predetermined offset “Offset _RSRP ” for each cell. Alternatively, “Offset _RSRQ ” or the like is managed.

Note that the threshold “Q _RSRPmin ” or “Q _RSRQmin ” and the predetermined offset “Offset _RSRP ” or “Offset _RSRQ ” may have different values for each cell, or may have values common to a plurality of cells. May be.

Further, the thresholds “Q _RSRPmin ” and “Q _RSRQmin ” may be referred to as “Thresh _{Serving, low} ”, “Thresh _{X, low} ”, “Thresh _{X, high} ”, and the like.

  Each information element included in the cell information may be notified as the above-described notification information or may be notified as the above-described individual signal.

  In the example of FIG. 3, the priority of the “own CSG cell” of the mobile station UE is “high”, the priority of the “macro cell” is “medium”, and the “other CSG cell” of the mobile station UE "Has a low priority. Note that the carrier frequency of the “own CSG cell” and the carrier frequency of the “other CSG cell” may be different or the same.

  The search location information management unit 15 is configured to manage search location information for defining a location where the mobile station UE should start searching for its own CSG cell.

  For example, the search location information management unit 15 may be configured to manage the “own CSG cell list” and the “superimposed macro cell list” received by the individual signal reception unit 12 as search location information. In this case, the “search place” is a macro cell included in the “superimposed macro cell list”.

  Further, the search location information management unit 15 independently generates the search location information (Finger Print) based on the “own CSG cell list” and the “superimposed macro cell list” received by the individual signal reception unit 12. It may be configured to manage. In such a case, the “search place” is a place defined by “GPS information” or the like.

  The search location information management unit 15 may be configured to generate and manage such search location information according to the propagation level of the cells in the “superimposed macro cell list”.

  The cell selection unit 16 selects a standby cell (mobile station UE) from among a CSG cell (a specific cell in which only a specific mobile station can be selected as a standby cell) and a macro cell (a general cell in which all mobile stations can be selected as a standby cell). Is configured to select a cell to be awaited.

  Further, as shown in FIG. 3, the cell selection unit 16 is configured to select a standby cell based on the priority of each cell.

  In the example of FIG. 3, with respect to the mobile station UE, cells # 1-1 and # 1-2 (own CSG cell) using the frequency f1 have “high” priority, and the cell # using the frequency f2 or f3 is used. 2-1, # 2-2, # 3-1, # 3-2 (macro cell) have a medium priority, cells # 4-1 and # 4-2 (other CSG cells using frequency f4) ) Is “low”. The frequencies f1 and f4 may be different frequencies or the same frequency.

Here, the cell selection unit 16 may select a cell having the same priority as that of the current standby cell of the mobile station UE as a standby cell of the mobile station UE in a predetermined cycle “T _Equal ”. It is configured to search for whether there is a cell that can be used.

Note that the cell selection unit 16 determines that the radio quality “Serving (RSRQ (Reference Signal Received Quality) or RSRP (Reference Signal Received Power))” in the current standby cell of the mobile station UE is greater than or _equal to the threshold “S _SearchEqual ”. You may be comprised so that a search may not be performed.

  For example, as shown in FIG. 3, the cell selection unit 16 uses the frequency f1 and uses “cell # 1-1” having a priority of “high” as a standby cell, and the predetermined condition A When (R-criteria) is satisfied, the standby cell is changed from “cell # 1-1” to “cell # 1-2” using the frequency f1 and having the priority “high”. It is configured as follows.

  As shown in FIG. 3, the cell selection unit 16 uses the frequency f2 and sets “cell # 2-1” having a priority of “medium” as a standby cell, and a predetermined condition A Is satisfied, the cell from “cell # 2-1” is using the frequency f2 and the priority is “medium”, or “cell # 2-2” or the frequency f3 is used. The priority is changed to “cell # 3-1” having “medium” (refer to the operation of FIG. 5 described later).

  Further, as shown in FIG. 3, the cell selection unit 16 uses the frequency f4 and uses “cell # 4-1” having a priority of “low” as a standby cell, and the predetermined condition A Is satisfied, the standby cell is configured to change from “cell # 4-1” to “cell # 4-2” using the frequency f4 and having the priority “low”. ing.

  Here, the cell selection unit 16 determines that the predetermined condition A is satisfied when the following expression (1) is satisfied.

“Neighbour” + “Offset _RSRP (or Offset _RSRQ ”> “Serving” + “Hysteresis” (1)
Note that “Neighbour” is an adjacent cell (“cell # 1-2”, “cell # 2-2”, “cell # 3-1”, or “cell # 4-2”) of the current standby cell of the mobile station UE. ), “Offset _RSRP (or Offset _RSRQ )” is a predetermined offset, and “Serving” is the current standby cell (“Cell # 1-1”, “Cell # 2-1” of the mobile station UE). 1 ”or“ cell # 4-1 ”), and“ Hysteresis ”is a predetermined parameter.

  For example, as illustrated in FIG. 3, when the cell selection unit 16 sets “cell # 1-2” as a standby cell and the predetermined condition B is satisfied, the cell selection unit 16 selects “cell # 1-2”. It is configured to change from “1-2” to “cell # 2-2”.

  In addition, when “cell # 3-2” is set as the standby cell and the predetermined condition B is satisfied, the cell selection unit 16 changes the standby cell from “cell # 3-2” to “cell # 4”. -2 "(see the operation of FIG. 6 described later).

Here, the cell selection unit 16 satisfies the second communication quality in a cell having the same priority as that of the current standby cell of the mobile station UE (that is, (radio quality “RSRP” or “RSRQ”) < (“Q _RSRPmin ” or “Q _RSRQmin ”) + (parameter “Margin”) is established) When the cell cannot be detected, the priority lower than the priority of the current standby cell of the mobile station UE And a cell satisfying the third radio quality (that is, (radio quality “RSRP” or “RSRQ”)> (“Q _RSRPmin ” or “Q _RSRQmin ”) + (parameter “Hysteresis”)) is detected It is determined that the predetermined condition B is satisfied.

In addition, the cell selection unit 16 may select a cell having a higher priority than the priority of the current standby cell of the mobile station UE as the standby cell of the mobile station UE in a predetermined cycle “T _Higher ”. It is configured to search for whether there is a cell that can be used.

Here, the predetermined periods “T _Equal ” and “T _Higher ” can be notified to the mobile station UE by the above-described broadcast information or individual signals. The predetermined periods “T _Equal ” and “T _Higher ” may be the same period or different periods.

  For example, as shown in FIG. 3, the cell selecting unit 16 selects “cell # 4-1” as the standby cell when “cell # 4-1” is the standby cell and the predetermined condition C is satisfied. 1 ”is changed to“ cell # 3-1 ”.

  Also, as shown in FIG. 3, the cell selection unit 16 uses “cell # 1-1” (the mobile station UE as the “specific mobile station” when “cell # 2-1” is the standby cell). If it is determined that the cell is located in “cell # 2-1 (general cell)” that is at least partially overlapped with “1 specific cell)” and the predetermined condition C is satisfied, the standby cell is designated as “cell # 2-1”. It is configured to change from “2-1” to “cell # 1-1” (see the operation of FIG. 4 described later).

Here, the cell selection unit 16 is the best among the cells in which the “RSRP or RSRQ (radio quality)” in the “cell # 1-1 (first specific cell)” uses the frequency f1 (first frequency), In addition, “RSRP or RSRQ (radio quality)” in “cell # 1-1 (first specific cell)” satisfies the first radio quality (ie, (radio quality “RSRP” or “RSRQ”))> (“Q _RSRPmin "or" _QRSRQmin ") may be established), it may be determined that the predetermined condition C is satisfied.

Further, the cell selection unit 16 performs the best “RSRP or RSRQ in a cell using“ RSRP or RSRQ (radio quality) ”in“ cell # 1-1 (first specific cell) ”and the frequency f1 (first frequency). (Radio Quality) ”is within a predetermined offset“ Offset _RSRP or Offset _RSRQ ”, and“ RSRP or RSRQ (Radio Quality) ”in“ Cell # 1-1 (First Specific Cell) ”is the first. When it is determined that the radio quality is satisfied (that is, (radio quality “RSRP” or “RSRQ”)> (“Q _RSRPmin ” or “Q _RSRQmin ”) is established), it is determined that the predetermined condition C is satisfied May be.

Furthermore, the cell selection unit 16 satisfies “RSRP or RSRQ (radio quality)” in “cell # 1-1 (first specific cell)” satisfies the first radio quality (that is, (radio quality “RSRP” or “RSRQ” ")>(" _QRSRPmin "or" _QRSRQmin ") is established), it may be determined that the predetermined condition C is satisfied.

(Operation of the mobile communication system according to the first embodiment of the present invention)
With reference to FIG. 4 thru | or FIG. 6, operation | movement of the mobile communication system which concerns on the 1st Embodiment of this invention is demonstrated.

  First, with reference to FIG. 4, an operation in which the mobile station UE changes the standby cell from “macro cell” to “own CSG cell” will be described.

  As illustrated in FIG. 4, in step S101, when the mobile station UE receives the “own CSG cell list” and the “superimposed macro cell list” from the switching apparatus MME, the mobile station UE is notified by the broadcast information for identifying the “macro cell”. By determining whether or not the “information (TA-ID and cell ID)” is included in the “superimposed macro cell list” included in the individual signal received from the switching apparatus MME, the mobile station UE at least in its own CSG cell It is determined whether or not it is located in a macro cell that is partially overlapped.

  Alternatively, in step S101, the mobile station UE refers to the search location information management unit 15 to determine whether or not the mobile station UE is located in the “search location”, so that the mobile station UE is at least partially in the own CSG cell. It is determined whether or not it is located in the macro cell to be superimposed.

  If the mobile station UE determines that the mobile station UE is located in the macro cell, the process of step S101 is repeated.

When it is determined that the mobile station UE is located in the macro cell, when it is detected in step S102 that the predetermined period “T _Higher ” has elapsed, whether or not there is a local CSG cell that satisfies the predetermined condition D in step S103. Determine whether or not.

  If the mobile station UE determines that there is a local CSG cell that satisfies the predetermined condition D, the mobile station UE changes the standby cell to a local CSG cell that satisfies the predetermined condition D in step S104.

  On the other hand, when the mobile station UE determines that there is no own CSG cell that satisfies the predetermined condition D, the operation returns to step S101.

  Secondly, with reference to FIG. 5, an operation in which the mobile station UE changes the standby cell from the “first macro cell” to the “second macro cell” will be described.

As illustrated in FIG. 5, when the mobile station UE detects that the predetermined period “T _Equal ” has elapsed in step S201, the radio quality “Serving (RSRP or RSRQ)” in the first macro cell is determined in step S202. , It is determined whether or not the threshold value is larger than “S _SearchEqual ”.

  When the determination result in step S201 is negative (NO), the operation returns to step S201.

  On the other hand, when the determination result in step S201 is affirmative (YES), the mobile station UE determines whether or not the following equation (2) is established in step S203.

(Radio quality "Neighbour (RSRP or RSRQ)" in the second macro cell adjacent to the first macro cell) + (predetermined offset "Offset _RSRP " or "Offset _RSRQ ")> (Radio quality "Serving (RSRP or RSRQ) in the first macro cell ) ") + (Parameter" Hysteresis ") (2)
When the determination result in step S203 is negative (NO), the operation returns to step S201.

  On the other hand, when the determination result in step S203 is affirmative (YES), the mobile station UE changes the standby cell from “first macro cell” to “second macro cell”.

  Thirdly, with reference to FIG. 6, the operation of the mobile station UE changing the standby cell from “macro cell” to “other CSG cell” will be described.

In step S301, can the mobile station UE detect a cell in which (radio quality “RSRP” or “RSRQ”) <(“Q _RSRPmin ” or “Q _RSRQmin ”) + (parameter “Margin”) is established? Determine whether or not.

  When the determination result in step S301 is negative (NO), the operation returns to step S301.

On the other hand, when the determination result in step S301 is affirmative (YES), in step S302, the mobile station UE determines that (radio quality “RSRP” or “RSRQ”)> (“ _QRSRPmin ” or “ _QRSRQmin ”) + ( It is determined whether or not a cell in which the parameter “Hysteresis”) is established can be detected.

  When the determination result in step S302 is negative (NO), in step S304, the mobile station UE detects that it is out of range.

  On the other hand, when the determination result in step S302 is affirmative (YES), in step S303, the mobile station UE selects the cell (other CSG cell) detected in step S302 as a standby cell.

(Operations and effects of the mobile communication system according to the first embodiment of the present invention)
The mobile communication system according to the present embodiment can appropriately select a standby cell in an environment where CSG cells and macro cells are mixed.

(Modification 1)
With reference to FIG. 7, the mobile communication system according to the first modification will be described focusing on differences from the mobile communication system according to the first embodiment described above.

  In the example of FIG. 7, with respect to the mobile station UE, the priority of the cell # 11 using the frequency f11 and the cell # 12 using the frequency f12 is “high”, and the cell # 21 and the frequency f22 using the frequency f21 are set. The priority of the cell # 22 to be used is “medium”, and the priority of the cell # 31 using the frequency f31 and the cell # 32 using the frequency f32 is “low”. Note that cells # 11, # 12, # 21, # 22, # 31 and # 32 may be macro cells or CSG cells. The frequencies f11, f12, f21, f22, f31, and f32 are different frequencies.

  For example, as illustrated in FIG. 7, when the cell selection unit 16 sets “cell # 11” as a standby cell and the predetermined condition A1 is satisfied, the cell selection unit 16 changes the standby cell from “cell # 11” to “cell # 11”. It is configured to change to “cell # 12”.

  As shown in FIG. 7, when the cell selection unit 16 sets “cell # 21” as a standby cell and the predetermined condition A1 is satisfied, the cell selection unit 16 changes the standby cell from “cell # 21” to “cell # 21”. It is configured to change to “cell # 22”.

  As shown in FIG. 7, when the cell selection unit 16 uses “cell # 31” as a standby cell and the predetermined condition A1 is satisfied, the cell selection unit 16 changes the standby cell from “cell # 31” to “ It is configured to change to “cell # 32”.

  Here, when “cell # 12”, “cell # 22”, or “cell # 32” is a macro cell, the cell selection unit 16 determines that the following formula (2) is satisfied, that is, “cell # 12”. 12 ”,“ cell # 22 ”or“ cell # 32 ”satisfies the predetermined radio quality, and the radio quality of“ cell # 11 ”,“ cell # 21 ”or“ cell # 31 ”is the predetermined radio quality. Is not satisfied, it is determined that the predetermined condition A1 is satisfied.

“Neighbour” + “Offset1”> “Threshold 1”, and
“Serving” + “Offset2” <“Threshold 2” (2)
Here, “Neighbour” is the radio quality in the adjacent cell (“cell # 12”, “cell # 22” or “cell # 32”) of the current standby cell of the mobile station UE, and “Serving” is the mobile It is the radio quality in the current standby cell (“cell # 11”, “cell # 21” or “cell # 31”) of the station UE.

  On the other hand, when “cell # 12”, “cell # 22”, or “cell # 32” is a CSG cell, the cell selector 16 determines that the following formula (3) is satisfied, that is, the above formula. In addition to the condition of (2), the difference between the radio quality in “cell # 12”, “cell # 22” or “cell # 32” and the best radio quality in the cell using the second frequency f12, f22 or f32 Is determined to be within the predetermined offset, it is determined that the predetermined condition A1 is satisfied.

“Neighbour” + “Offset1”> “Threshold 1”, and
“Serving” + “Offset2” <“Threshold 2”, and
“Neighbour”> “R0” − “Offset3” (3)
Here, “R0” is a frequency (f12, f22, or f32) used in a neighboring cell (“cell # 12”, “cell # 22”, or “cell # 32”) of the current standby cell of the mobile station UE. ) And the radio quality of the cell with the best radio quality using the same frequency.

  For example, as illustrated in FIG. 7, when the cell selection unit 16 sets “cell # 12” as a standby cell and the predetermined condition B1 is satisfied, the cell selection unit 16 sets the standby cell as “cell # 12”. To “cell # 22”.

  Further, the cell selection unit 16 changes the standby cell from “cell # 22” to “cell # 32” when “cell # 22” is the standby cell and when the predetermined condition B1 is satisfied. It is configured as follows.

  Here, when “cell # 22” or “cell # 32” is a macro cell, the cell selection unit 16 determines that “cell # 22” or “cell # 22” is satisfied when the following equation (4) is satisfied. When the wireless quality at “32” satisfies the predetermined wireless quality and the wireless quality of “cell # 11” or “cell # 21” does not satisfy the predetermined wireless quality, it is determined that the predetermined condition B1 is satisfied.

“Neighbour” + “Offset4”> “Threshold 3”, and
“Serving” + “Offset5” <“Threshold 4” (4)
Here, “Neighbour” is the radio quality in the adjacent cell (“cell # 22” or “cell # 32”) of the current standby cell of the mobile station UE, and “Serving” is the current standby of the mobile station UE. It is the radio quality in the cell (“cell # 12” or “cell # 22”).

  In addition to the case where the above-described equation (4) is satisfied, the cell selection unit 16 performs the case where the following equation (4-1) is satisfied, that is, the current standby cell (“cell # 12” of the mobile station UE). ”Or“ cell # 22 ”), the predetermined condition B1 is satisfied when there is no cell satisfying the predetermined radio quality among the cells using the same frequency (f12 or f22) used in the cell You may judge.

“X” + “Offset5” <“Threshold 4” Expression (4-1)
Here, “X” is the radio of each cell using the same frequency as the frequency (f12 or f22) used in the current standby cell (“cell # 12” or “cell # 22”) of the mobile station UE. Show quality.

  On the other hand, when “cell # 22” or “cell # 32” is a CSG cell, the cell selection unit 16 determines that the following expression (5) is satisfied, that is, the condition of the above expression (4) is satisfied. In addition, when it is determined that the difference between the radio quality in “cell # 22” or “cell # 32” and the best radio quality in the cell using the second frequency f22 or f32 is within a predetermined offset, the predetermined condition It is determined that B1 is satisfied.

“Neighbour” + “Offset4”> “Threshold 3”, and
“Serving” + “Offset5” <“Threshold 4”, and
“Neighbour”> “R0” − “Offset6” (5)
Here, “R0” is the highest frequency that uses the same frequency (f22 or f32) used in the neighboring cell (“cell # 22” or “cell # 32”) of the current standby cell of the mobile station UE. It is the radio quality of a cell with good radio quality.

  In addition to the case where the above-described equation (5) is satisfied, the cell selection unit 16 performs the case where the following equation (5-1) is satisfied, that is, the current standby cell (“cell # 12” of the mobile station UE). ”Or“ cell # 22 ”), the predetermined condition B1 is satisfied when there is no cell satisfying the predetermined radio quality among the cells using the same frequency (f12 or f22) used in the cell You may judge.

“X” + “Offset5” <“Threshold 4” Expression (5-1)
Here, “X” is the radio of each cell using the same frequency as the frequency (f12 or f22) used in the current standby cell (“cell # 12” or “cell # 22”) of the mobile station UE. Show quality.

  For example, as illustrated in FIG. 7, when the cell selection unit 16 sets “cell # 31” as the standby cell and the predetermined condition C1 is satisfied, the cell selection unit 16 changes the standby cell from “cell # 31” to “cell # 31”. It is configured to change to “cell # 21”.

  As shown in FIG. 7, the cell selection unit 16 selects “cell # 21” from “cell # 21” to “cell # 21” when the predetermined cell C1 is satisfied when “cell # 21” is the standby cell. 11 ”.

  Here, when “cell # 11” or “cell # 21” is a macro cell, the cell selection unit 16 determines that “cell # 11” or “cell # 11” is satisfied when the following equation (6) is satisfied. When the radio quality in “21” satisfies the predetermined radio quality, it is determined that the predetermined condition C1 is satisfied.

“Neighbour” + “Offset7”> “Threshold 5” (6)
Here, “Neighbour” is the radio quality in the adjacent cell (“cell # 11” or “cell # 21”) of the current standby cell of the mobile station UE.

  On the other hand, when “cell # 11” or “cell # 21” is a CSG cell, the cell selector 16 determines that the following equation (7) is satisfied, that is, the condition of the above equation (6) is satisfied. In addition, when it is determined that the difference between the radio quality in “cell # 11” or “cell # 21” and the best radio quality in the cell using the second frequency f11 or f21 is within a predetermined offset, the predetermined condition It is determined that A1 is satisfied.

“Neighbour” + “Offset7”> “Threshold 5”, and
“Neighbour”> “R0” − “Offset8” (7)
Here, “R0” is the highest frequency that uses the same frequency (f11 or f21) used in the neighboring cell (“cell # 11” or “cell # 21”) of the current standby cell of the mobile station UE. It is the radio quality of a cell with good radio quality.

  The operations of the mobile station UE, the radio base station eNB, the home base station HNB, and the switching device MME described above may be implemented by hardware or may be implemented by a software module executed by a processor, You may implement by the combination of both.

  The software module includes a RAM (Random Access Memory), a flash memory, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electronically Erasable and Programmable ROM, a hard disk, a registerable ROM, a hard disk). Alternatively, it may be provided in a storage medium of an arbitrary format such as a CD-ROM.

  Such a storage medium is connected to the processor so that the processor can read and write information from and to the storage medium. Further, such a storage medium may be integrated in the processor. Such a storage medium and processor may be provided in the ASIC. Such an ASIC may be provided in the mobile station UE and the radio base station eNB. Moreover, this storage medium and processor may be provided in the mobile station UE and the radio base station eNB as a discrete component.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

UE ... mobile station 11 ... broadcast information receiving unit 12 ... individual signal receiving unit 13 ... parameter storage unit 14 ... cell information management unit 15 ... search location information management unit 16 ... cell selection unit eNB ... radio base station HNB ... home base station MME ... Exchanger

Claims (22)

A cell selection method in which a mobile station selects a standby cell from a specific cell that can be selected only as a standby cell by a specific mobile station and a general cell in which all mobile stations can be selected as standby cells.
When the mobile station uses the first general cell as a standby cell, the process A determines whether or not a predetermined condition is satisfied;
A cell selection method comprising: a step B of changing the standby cell from the first general cell to the first specific cell when the mobile station determines that the predetermined condition is satisfied.   In the step A, the mobile station uses the first general cell as a standby cell, and the mobile station is at least partially overlapped with a first specific cell having the mobile station as the specific mobile station. The cell selection method according to claim 1, wherein if it is determined that the cell is located, it is determined whether or not the predetermined condition is satisfied. The first frequency used in the first specific cell is different from the second frequency used in the first general cell,
In the step A, the mobile station has the best radio quality in the first specific cell among the cells using the first frequency, and the radio quality in the first specific cell satisfies the first radio quality. 2, when it is determined that the predetermined condition is satisfied, the standby cell is changed from the first general cell to the first specific cell in the step B. Cell selection method. The first frequency used in the first specific cell is different from the second frequency used in the first general cell,
In the step A, the mobile station determines that the difference between the radio quality in the first specific cell and the best radio quality in the cell using the first frequency is within a predetermined offset, and in the first specific cell When it is determined that the radio quality satisfies the first radio quality, it is determined that the predetermined condition is satisfied, and the standby cell is changed from the first general cell to the first specific cell in the step B. The cell selection method according to claim 1.   In the step A, when the mobile station determines that the radio quality in the first specific cell satisfies the first radio quality, the mobile station determines that the predetermined condition is satisfied. In the step B, the mobile station The cell selection method according to claim 1, wherein the cell is changed from the first general cell to the first specific cell.   When the mobile station can no longer detect a general cell that satisfies the second radio quality, and when it detects a second specific cell that satisfies the third radio quality that does not make the mobile station the specific mobile station The cell selecting method according to claim 1, further comprising a step C of setting the second specific cell as a standby cell.   When the mobile station uses the second specific cell as a standby cell and detects a second general cell that satisfies the second radio quality, the mobile station moves from the second specific cell to the second general cell. The cell selection method according to claim 6, further comprising a step of changing to: A mobile station configured to select a standby cell from a specific cell that can be selected only as a standby cell by a specific mobile station and a general cell in which all mobile stations can be selected as standby cells,
When the first general cell is a standby cell, it is determined whether or not a predetermined condition is satisfied. If it is determined that the predetermined condition is satisfied, the standby cell is moved from the first general cell to the first cell. A mobile station comprising a cell selection unit configured to change to a specific cell.   The cell selection unit determines that the first general cell is a standby cell and is located in a general cell that is at least partially overlapped with the first specific cell having the mobile station as the specific mobile station. The mobile station according to claim 8, wherein the mobile station is configured to determine whether or not the predetermined condition is satisfied. The first frequency used in the first specific cell is configured to be different from the second frequency used in the first general cell,
When the cell selection unit determines that the radio quality in the first specific cell is the best among the cells using the first frequency, and the radio quality in the first specific cell satisfies the first radio quality The mobile station according to claim 8, wherein the mobile station is configured to determine that the predetermined condition is satisfied and to change a standby cell from the first general cell to the first specific cell. . The first frequency used in the first specific cell is configured to be different from the second frequency used in the first general cell,
The cell selection unit is configured such that a difference between a radio quality in the first specific cell and a best radio quality in a cell using the first frequency is within a predetermined offset, and the radio quality in the first specific cell is When it is determined that one radio quality is satisfied, it is determined that the predetermined condition is satisfied, and the standby cell is changed from the first general cell to the first specific cell. The mobile station according to claim 8.   When the cell selection unit determines that the radio quality in the first specific cell satisfies the first radio quality, the cell selection unit determines that the predetermined condition is satisfied, and determines a standby cell from the first general cell to the first general cell. The mobile station according to claim 8, wherein the mobile station is configured to change to one specific cell.   The cell selection unit has detected a second specific cell that satisfies a third radio quality when it is no longer possible to detect a general cell that satisfies the second radio quality and the mobile station is not the specific mobile station. In this case, the mobile station according to any one of claims 8 to 12, wherein the second specific cell is configured as a standby cell.   When the cell selection unit uses the second specific cell as a standby cell and detects a second general cell that satisfies the second radio quality, the cell selection unit determines the standby cell from the second specific cell to the second general cell. The mobile station according to claim 13, wherein the mobile station is configured to change to a cell. A cell selection method in which a mobile station selects a standby cell from among a first cell using a first frequency and a second cell using a second frequency different from the first frequency,
When the priority of the second cell is higher than the priority of the first cell, the mobile station using the first cell as a standby cell determines that the radio quality in the second cell satisfies a predetermined radio quality. In this case, the cell selection method includes a step of changing the standby cell from the first cell to the second cell. A cell selection method in which a mobile station selects a standby cell from among a first cell using a first frequency and a second cell using a second frequency different from the first frequency,
When the priority of the second cell is the same as the priority of the first cell, the mobile station that uses the first cell as a standby cell satisfies the radio quality in the second cell satisfying a predetermined radio quality, A cell selection method comprising: changing a standby cell from the first cell to the second cell when it is determined that the radio quality of the first cell does not satisfy a predetermined radio quality. A cell selection method in which a mobile station selects a standby cell from among a first cell using a first frequency and a second cell using a second frequency different from the first frequency,
When the priority of the second cell is lower than the priority of the first cell, the mobile station using the first cell as a standby cell satisfies the radio quality in the second cell satisfying a predetermined radio quality, and A cell selection method comprising: changing a standby cell from the first cell to the second cell when it is determined that the radio quality of the first cell does not satisfy a predetermined radio quality.   When the second cell is a specific cell that can be selected only as a standby cell by the specific mobile station, the mobile station further selects the second cell in the cell using the radio quality and the second frequency. 18. The standby cell is changed from the first cell to the second cell when it is determined that the difference from the good radio quality is within a predetermined offset. 18. Cell selection method. A mobile station configured to select a standby cell from among a first cell using a first frequency and a second cell using a second frequency different from the first frequency,
When the priority of the second cell is higher than the priority of the first cell, it is determined that the first cell is a standby cell and the radio quality in the second cell satisfies a predetermined radio quality. In this case, the mobile station includes a cell selection unit configured to change the standby cell from the first cell to the second cell. A mobile station configured to select a standby cell from among a first cell using a first frequency and a second cell using a second frequency different from the first frequency,
When the priority of the second cell is the same as the priority of the first cell, the first cell is a standby cell, and the radio quality in the second cell satisfies a predetermined radio quality, And a cell selection unit configured to change the standby cell from the first cell to the second cell when it is determined that the radio quality of the first cell does not satisfy the predetermined radio quality. A mobile station characterized by A mobile station configured to select a standby cell from among a first cell using a first frequency and a second cell using a second frequency different from the first frequency,
When the priority of the second cell is lower than the priority of the first cell, the first cell is a standby cell, and the radio quality in the second cell satisfies a predetermined radio quality, and A cell selection unit configured to change the standby cell from the first cell to the second cell when it is determined that the radio quality of the first cell does not satisfy the predetermined radio quality. A featured mobile station.   When the second cell is a specific cell that can be selected as a standby cell only by a specific mobile station, the cell selection unit further includes a radio quality in the second cell and a cell using the second frequency. 22. The apparatus according to claim 19, wherein the standby cell is changed from the first cell to the second cell when it is determined that the difference from the best radio quality is within a predetermined offset. The mobile station as described in any one of.

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