JP4339351B2 - Mobile station and communication method - Google Patents

Description

  A mobile station and a communication method for receiving a control signal from a base station at an intermittent reception period before the start of communication is detected and continuously receiving a control signal from the base station after the start of communication is detected About.

  Conventionally, a communication system having a plurality of cells managed by a plurality of base stations is known. In this communication system, since the mobile station moves across a plurality of cells, it is necessary to change the cell in which the mobile station should be located (the base station to which the mobile station should communicate).

  Therefore, the mobile station evaluates the reception quality of a control signal received from each base station (for example, a common pilot signal received via a common pilot channel (CPICH)) in order to select an optimal cell (base station). (Hereinafter, cell evaluation processing) is performed. Next, when the reception quality of the cell where the mobile station is located (hereinafter referred to as the cell in which the mobile station is located) deteriorates compared to the reception quality of the cell located in the vicinity of the serving cell (hereinafter referred to as the neighboring cell), the mobile station The in-zone cell of the station is changed (for example, Patent Document 1).

  Here, in the cell evaluation process, since it is necessary to receive a control signal from each base station, if the mobile station always performs the cell evaluation process, the battery of the mobile station is consumed significantly.

  Therefore, when the mobile station is in a standby state, the mobile station intermittently receives a control signal from each base station, and cell evaluation processing is performed based on the reception quality of the control signal received intermittently ( Hereinafter, intermittent reception state). On the other hand, when the mobile station is in a communication state, the mobile station continuously receives control signals from each base station, and cell evaluation processing is performed based on the reception quality of the received control signals. (Hereafter, continuous reception state).

  Hereinafter, an operation of the mobile station shifting from the intermittent reception state to the continuous reception state when the mobile station shifts from the standby state to the communication state will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a case where a mobile station shifts from an intermittent reception state to a continuous reception state when the mobile station moves from cell A to cell B.

  As shown in FIG. 1, in the intermittent reception state, the mobile station hardware receives a control signal (common pilot signal) at an intermittent reception cycle. Subsequently, the hardware of the mobile station notifies the software of a measurement result report indicating the reception quality of the control signal. The mobile station software determines whether or not to perform cell reselection processing based on the measurement result report.

  On the other hand, in the continuous reception state, the mobile station hardware continuously receives the control signal (common pilot signal). Subsequently, the hardware of the mobile station notifies the measurement result report indicating the reception quality of the control signal continuously received during the cell evaluation period to the software. The mobile station software determines whether or not to perform cell reselection processing based on the measurement result report.

  It should be noted that the cell evaluation period is a certain period or longer in order to reduce the influence of temporary deterioration of the reception quality of the control signal (common pilot signal) due to fading or the like.

  Here, consider the case where the mobile station software accepts outgoing (or incoming). The mobile station software shifts the hardware to a state in which a control signal can be received via FACH (Forward Access Channel). FACH is a channel for transmitting a downlink control signal from a serving cell to a mobile station.

  The mobile station software shifts the hardware to a state where a control signal can be transmitted via a RACH (Random Access Channel). RACH is a channel for transmitting an uplink control signal from a mobile station toward a serving cell. The RACH is used to determine the initial transmission power of a signal transmitted from a serving cell to a mobile station before RRC (Radio Resource Control) CONNECTION is set.

  When the start of communication is detected, the mobile station software transmits a connection request (RRC CONNECTION REQUEST) for requesting the setting of RRC CONNECTION to the serving cell in parallel with the cell evaluation process. That is, the connection request (RRC CONNECTION REQUEST) is transmitted to the serving cell (cell A) even during the cell evaluation period.

  FIG. 1 illustrates a case where it is determined that the cell reselection process is performed based on the measurement result report. Therefore, the software of the mobile station notifies the hardware of a broadcast information reception command that instructs reception of broadcast information of the neighboring cell (cell B). Subsequently, the mobile station determines whether or not to change the serving cell after receiving the broadcast information of the neighboring cell (cell B) (cell reselection process).

  FIG. 1 illustrates a case where the serving cell is changed from cell A to cell B based on the broadcast information. Accordingly, the hardware of the mobile station notifies the software of a status report (Measurement result on RACH) including the reception quality of the control signal (common pilot signal) received from the cell B. The mobile station software transmits a connection request (RRC CONNECTION REQUEST) requesting the setting of RRC CONNECTION to cell B. The cell B transmits a setting completion (RRC CONNECTION SETUP) indicating that the RRC CONNECTION is set to the mobile station.

JP 2004-242017 (etc.)

  Here, as shown in FIG. 1, when the mobile station shifts from the intermittent reception state to the continuous reception state, the cycle for determining whether or not to perform cell reselection processing (cell reselection cycle) is intermittent reception. This is a cycle obtained by adding the cycle and the cell evaluation period.

  Therefore, depending on the moving speed of the mobile station, the change of the serving cell may not be able to follow the movement of the mobile station. That is, the mobile station may not be able to be located in the optimal cell. As a result, a reconnection operation may be required after the mobile station starts communication, or communication may be disconnected.

  In addition, when a mobile station performs transmission, a transmission delay occurs with an increase in the cell reselection period by securing the cell evaluation period.

  Therefore, the present invention has been made to solve the above-described problem, and it is possible to shorten the cell reselection period when the mobile station shifts from the intermittent reception state to the continuous reception state. It is an object to provide a mobile station and a communication method.

  One feature of the present invention is that, before the start of communication is detected, a control signal is received at an intermittent reception period from the serving cell and neighboring cells, and after the start of communication is detected, Based on the reception quality of the control signal received in the intermittent reception period from the serving cell and the neighboring cell, the receiving unit (receiving unit 31) that continuously receives the control signal from the cell and the neighboring cell, A first determination unit (cell evaluation unit 35A) that determines whether or not to perform cell reselection processing that is processing for reselecting the in-zone cell, and continuous from the in-zone cell and the neighboring cells within a cell evaluation period A second determination unit (cell evaluation unit 35A) that determines whether or not to perform the cell reselection process based on reception quality of the control signal received automatically, and the cell after the start of the communication is detected Evaluation period has passed Before, the 3rd determination part (cell evaluation part 35A) which determines whether the reception quality of the said control signal received from the said serving cell exceeds a predetermined threshold value, the said 1st determination part, the said 2nd determination part Alternatively, the mobile station includes a cell reselection processing unit (cell evaluation unit 35A) that performs the cell reselection processing according to a determination result by the third determination unit, and the cell reselection processing unit When it is determined by the third determination unit that the reception quality exceeds a predetermined threshold, the cell reselection process is performed according to the determination result by the second determination unit after waiting for the cell evaluation period to elapse. The gist is to perform the cell reselection processing without waiting for the elapse of the cell evaluation period when the third determination unit determines that the reception quality of the control signal is equal to or lower than a predetermined threshold.

  According to this feature, the third determination unit determines whether the reception quality of the control signal received from the serving cell exceeds a predetermined threshold before the cell evaluation period elapses after the start of communication is detected. To do. The cell reselection processing unit performs the cell reselection processing without waiting for the cell evaluation period to elapse when it is determined that the reception quality of the control signal is equal to or lower than the predetermined threshold.

  That is, when the reception quality of the control signal received from the serving cell is degraded, an opportunity to perform the cell reselection process is obtained before the cell evaluation period elapses after the start of communication is detected. Therefore, it is possible to suppress the occurrence of a reconnection operation, communication disconnection, transmission delay, and the like due to an extended period (cell reselection period) for determining whether or not to perform cell reselection processing.

  As described above, when the mobile station shifts from the intermittent reception state to the continuous reception state, the cell reselection cycle can be shortened.

  On the other hand, when it is determined that the reception quality of the control signal exceeds the predetermined threshold, the cell reselection processing unit waits for the cell evaluation period to elapse and performs cell reselection according to the determination result by the second determination unit Process. Therefore, as in the past, it is possible to reduce the influence of temporary deterioration of the reception quality of the control signal due to fading or the like, and to select the optimum cell that the station should be in.

  One feature of the present invention is that, in the one feature described above, the mobile station further includes a transmitter that transmits a connection request for requesting connection to the serving cell when the start of the communication is detected. When the transmission unit determines that the reception quality of the control signal is equal to or lower than a predetermined threshold by the third determination unit, the transmission unit stops transmitting the connection request until the cell reselection process is completed. The gist.

  One feature of the present invention is that, before the start of communication is detected, a control signal is received at an intermittent reception period from the serving cell and neighboring cells, and after the start of communication is detected, In a communication system including a mobile station that continuously receives the control signal from a cell and the neighboring cell, a communication method in which the mobile station reselects the serving cell is intermittent from the serving cell and the neighboring cell. Determining whether or not to perform cell reselection processing, which is processing for reselecting the serving cell, based on reception quality of the control signal received in a reception cycle; and the serving cell and the neighboring cell The step B for determining whether or not to perform the cell reselection process based on the reception quality of the control signal continuously received within the cell evaluation period from the start of the communication after the start of the communication is detected. Step C for determining whether the reception quality of the control signal received from the serving cell exceeds a predetermined threshold before the evaluation period elapses, and the determination result in Step A, Step B, or Step C And the step D for performing the cell reselection process. In the step D, if it is determined in the step C that the reception quality of the control signal exceeds a predetermined threshold value, the determination in the step B is performed. Waiting for the result, the cell reselection process is performed, and if it is determined in step C that the reception quality of the control signal is equal to or lower than a predetermined threshold, the cell reselection is not performed without waiting for the determination result in step B. The gist is to perform the selection process.

  ADVANTAGE OF THE INVENTION According to this invention, when a mobile station transfers to a continuous reception state from an intermittent reception state, the mobile station and communication method which can shorten a cell reselection period can be provided.

  Hereinafter, a communication system according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[First Embodiment]
(Outline of communication system)
The outline of the communication system according to the first embodiment will be described below with reference to the drawings. FIG. 2 is a diagram illustrating an outline of the communication system according to the first embodiment.

  As shown in FIG. 2, the communication system moves across a plurality of base stations 10 (base station 10A and base station 10B) that respectively manage a plurality of cells 20 (cell 20A and cell 20B) and a plurality of cells 20. And a plurality of possible mobile stations 30. It should be noted that a cell where the mobile station 30 is located is referred to as a visited cell. Specifically, the serving cell is a cell in which the position of the mobile station 30 is registered. In addition, a cell located in the vicinity of the serving cell is referred to as a neighboring cell.

  The base station 10 periodically transmits a control signal (common pilot signal) via CPICH (Common Pilot Channel). The base station 10 communicates with the mobile station 30 located in the cell 20 managed by the base station 10. Specifically, the base station 10 transmits a data signal to the mobile station 30 via DPCH (Dedicated Physical Channel) or the like. Similarly, the base station 10 receives a data signal from the mobile station 30 via DPCH or the like.

  The mobile station 30 receives control signals (common pilot signals) from the serving cell and the neighboring cells where the mobile station is located. The mobile station 30 communicates with the base station 10 that manages the cell in which the mobile station is located. Specifically, the mobile station 30 transmits a data signal to the base station 10 via DPCH or the like. Similarly, the mobile station 30 receives a data signal from the base station 10 via DPCH or the like.

(Configuration of mobile station)
The configuration of the mobile station according to the first embodiment will be described below with reference to the drawings. FIG. 3 is a block diagram showing a configuration of the mobile station 30 according to the first embodiment.

  As illustrated in FIG. 3, the mobile station 30 includes a reception unit 31, an intermittent reception cycle timer 32, a cell evaluation period timer 33, a reception quality measurement unit 34, a control unit 35, and a transmission unit 36.

  The receiving unit 31 receives a control signal (common pilot signal) from the serving cell and neighboring cells. The receiving unit 31 receives a control signal (such as broadcast information transmitted via a P-CCPCH (Primary Common Control Physical Channel)) from the serving cell and the neighboring cells. The receiving unit 31 receives control signals (such as a paging display signal transmitted via a PICH (Paging Indication Channel) and paging information transmitted via an S-CCPCH (Secondary Common Control Physical Channel)) from the serving cell. To do.

  Of course, the receiving unit 31 receives a data signal from a serving cell via a DPCH (Dedicated Physical Channel) or the like.

  Here, before the start of communication is detected (standby state), the receiving unit 31 intermittently sends control signals (common pilot signals) from the serving cell and the neighboring cells according to the value of the intermittent reception cycle timer 32 described later. (Intermittent reception status). On the other hand, after the start of communication is detected (communication state), the receiving unit 31 continuously receives control signals (common pilot signals) from the serving cell and neighboring cells (continuous reception state).

  The intermittent reception cycle timer 32 measures a cycle (intermittent reception cycle) in which the control signal (common pilot signal) is intermittently received before the start of communication is detected. The cell evaluation period timer 33 measures a period (cell evaluation period) in which a control signal (common pilot signal) is continuously received in order to perform cell evaluation processing after the start of communication is detected. The cell evaluation process is a process for determining whether or not to perform a cell reselection process for reselecting an optimum cell that the local station should be in.

  The reception quality measurement unit 34 measures the reception quality of the control signal (common pilot signal) received by the reception unit 31. Here, the reception quality is Ec / NO (energy to received power density ratio), RSCP (Received Signal Code Power), or the like.

  Specifically, in the intermittent reception state (standby state), the reception quality measurement unit 34 measures the reception quality of the control signal (common pilot signal) received intermittently from the serving cell. Subsequently, when the reception quality of the control signal (common pilot signal) is less than a predetermined determination value, the reception quality measurement unit 34 receives the control signal (common pilot signal) received intermittently from the neighboring cells. Measure quality.

  On the other hand, in the continuous reception state (communication state), the reception quality measurement unit 34 measures the reception quality of the control signal (common pilot signal) continuously received from the serving cell within the cell evaluation period. Subsequently, when the reception quality of the control signal (common pilot signal) is less than a predetermined determination value, the reception quality measuring unit 34 controls the control signal (commonly received from neighboring cells within the cell evaluation period). Measure the reception quality of the pilot signal.

  Here, it should be noted that the reception quality measurement unit 34 measures the reception quality of the control signal (common pilot signal) received from the serving cell before the cell evaluation period elapses after the start of communication is detected. It is. In this case, it is preferable that the reception quality measurement unit 34 measures the reception quality of the control signal (common pilot signal) received first from the serving cell after the start of communication is detected.

  It should be noted that the reception quality of the control signal (common pilot signal) received from the serving cell is included in the status report (Measurement result on RACH).

  The control unit 35 includes a cell evaluation unit 35A that performs comparative evaluation between the serving cell and neighboring cells, and a communication processing unit 35B that performs processing necessary for communication performed between the mobile station 30 and the base station 10. .

  The cell evaluation unit 35A determines whether or not to perform the cell reselection process based on the reception quality measured by the reception quality measurement unit 34. Here, the cell evaluation unit 35A receives the control signal (common pilot signal) from the neighboring cell when the reception quality of the control signal (common pilot signal) received from the serving cell is less than a predetermined determination value. Instruct. Subsequently, the cell evaluation unit 35A compares the reception quality of the control signal (common pilot signal) received from the serving cell with the reception quality of the control signal (common pilot signal) received from the neighboring cell. The cell evaluation unit 35A determines that the cell reselection process is performed when the neighboring cell is more appropriate than the serving cell. When it is determined that the cell reselection process is to be performed, the cell evaluation unit 35A is based on the broadcast information received by the reception unit 31 (such as a control signal received via the P-CCPCH). The optimum cell to be serviced is reselected (cell reselection process).

  Specifically, in the intermittent reception state (standby state), the cell evaluation unit 35A performs cell reselection based on the reception quality of the control signal (common pilot signal) received intermittently from the serving cell and the neighboring cells. It is determined whether to perform processing. Subsequently, the cell evaluation unit 35A reselects the optimum cell that the own station should be in based on the broadcast information received by the reception unit 31 (such as a control signal received via the P-CCPCH).

  On the other hand, in the continuous reception state (communication state), the cell evaluation unit 35A determines whether the cell is based on the reception quality of the control signal (common pilot signal) continuously received from the serving cell and the neighboring cells in the cell evaluation period. It is determined whether or not reselection processing is performed. Subsequently, the cell evaluation unit 35A reselects the optimum cell that the own station should be in based on the broadcast information received by the reception unit 31 (such as a control signal received via the P-CCPCH).

  Here, the cell evaluation unit 35A determines whether the reception quality of the control signal (common pilot signal) received from the serving cell before the elapse of the cell evaluation period after the start of communication is detected exceeds a predetermined threshold value. It should be noted that the judgment is made. When the reception quality of the control signal (common pilot signal) exceeds a predetermined threshold, the cell evaluation unit 35A waits for the cell evaluation period to elapse and continuously receives the control signal (common pilot signal) within the cell evaluation period. ) To perform cell reselection processing according to the determination result based on the reception quality. On the other hand, when the reception quality of the control signal (common pilot signal) is equal to or lower than the predetermined threshold, the cell evaluation unit 35A performs the cell reselection process without waiting for the cell evaluation period to elapse.

  In this case, the cell evaluation unit 35A preferably determines whether or not the reception quality of the control signal (common pilot signal) first received from the serving cell after the start of communication is detected exceeds a predetermined threshold value. .

  Here, the status report (Measurement result on RACH) includes the reception quality of the control signal (common pilot signal) received from the serving cell. Therefore, it should be noted that the cell evaluation unit 35A can divert the reception quality included in the status report (Measurement result on RACH) when determining whether or not to perform the cell reselection process. .

  When the start of communication is detected, the communication processing unit 35B instructs the transmission unit 36 to transmit a connection request (RRC CONNECTION REQUEST) for requesting connection to the serving cell. Here, when the reception quality of the control signal (common pilot signal) received from the serving cell before the cell evaluation period elapses after the start of communication is detected, the communication processing unit 35B is not more than a predetermined threshold value. Note that the transmission of the connection request (RRC CONNECTION REQUEST) is stopped until the cell reselection process is completed.

  The transmission unit 36 transmits RACH (Random Access Channel) including the status report to the serving cell. The transmission unit 36 transmits a connection request (RRC CONNECTION REQUEST) to the serving cell in response to an instruction from the communication processing unit 35B.

  Of course, the transmission unit 36 transmits a data signal such as DPCH (Dedicated Physical Channel) to the serving cell.

(Transition from intermittent reception state to continuous reception state)
Hereinafter, in the first embodiment, an outline of the transition from the intermittent reception state to the continuous reception state will be described with reference to the drawings. FIG. 4 is a diagram illustrating an outline of the transition from the intermittent reception state to the continuous reception state in the first embodiment. Here, the hardware is, for example, the reception unit 31, the intermittent reception cycle timer 32, the cell evaluation period timer 33, the reception quality measurement unit 34, and the transmission unit 36, and the software is, for example, the control unit described above. Note that it is 35.

  As shown in FIG. 4, in the intermittent reception state, the hardware of the mobile station 30 receives the control signal (common pilot signal) at the intermittent reception cycle. Subsequently, the hardware of the mobile station 30 notifies the software of a measurement result report indicating the reception quality of the control signal. The software of the mobile station 30 determines whether or not to perform cell reselection processing based on the measurement result report.

  On the other hand, in the continuous reception state, the hardware of the mobile station 30 continuously receives the control signal (common pilot signal). Subsequently, the hardware of the mobile station 30 notifies the measurement result report indicating the reception quality of the control signal continuously received within the cell evaluation period to the software. The software of the mobile station 30 determines whether or not to perform cell reselection processing based on the measurement result report.

  It should be noted that the cell evaluation period is a certain period or longer in order to reduce the influence of temporary deterioration of the control signal (common pilot signal) due to fading or the like.

  Here, consider a case where the mobile station 30 software receives a call (or call). The software of the mobile station 30 shifts the hardware to a state in which the control signal can be received via the FACH (Forward Access Channel). The FACH is a channel for transmitting a downlink control signal from the serving cell to the mobile station 30.

  The software of the mobile station 30 shifts the hardware to a state where a control signal can be transmitted via a RACH (Random Access Channel). The RACH is a channel for transmitting an uplink control signal from the mobile station 30 toward the serving cell. The RACH is used to determine the initial transmission power of a signal transmitted from the serving cell to the mobile station 30 before the RRC CONNECTION is set. The control signal transmitted via the RACH includes a status report including the reception quality of the control signal (common pilot signal) received from the serving cell.

  Here, when transmitting the control signal via the RACH, the software of the mobile station 30 requests the hardware to report the reception quality of the control signal (common pilot signal), and the reception reported from the hardware. Quality is included in the status report (Measurement result on RACH). The software of the mobile station 30 determines whether or not the reception quality of the control signal (common pilot signal) included in the status report exceeds a predetermined threshold value.

  FIG. 4 illustrates a case where the reception quality of the control signal (common pilot signal) is equal to or lower than a predetermined threshold value. Therefore, the software of the mobile station 30 notifies the hardware of a broadcast information reception command instructing reception of broadcast information for the neighboring cell (cell B). Subsequently, the mobile station 30 receives broadcast information about the neighboring cell (cell B), and then reselects the optimal cell in which the mobile station should be located (cell reselection process).

  FIG. 4 illustrates a case where the serving cell is changed from the cell A to the cell B. Therefore, the software of the mobile station 30 notifies the hardware of the change of the serving cell (cell selection). Subsequently, the hardware of the mobile station 30 notifies the software of a status report (Measurement result on RACH) including the reception quality of the control signal (common pilot signal) received from the cell B. The mobile station software transmits a connection request (RRC CONNECTION REQUEST) requesting the setting of RRC CONNECTION to cell B. The cell B transmits a setting completion (RRC CONNECTION SETUP) indicating that the RRC CONNECTION is set to the mobile station.

  Here, when the reception quality of the control signal (common pilot signal) included in the status report (Measurement result on RACH) is equal to or lower than a predetermined threshold, the software of the mobile station 30 connects until the cell reselection process is completed. It should be noted that the transmission of the request (RRC CONNECTION REQUEST) is stopped.

(Mobile station operation)
Hereinafter, the operation of the mobile station according to the first embodiment will be described with reference to the drawings. 5 and 6 are flowcharts showing the configuration of the mobile station 30 according to the first embodiment.

  First, a process for determining whether or not to change a cell (local cell) in which the local station should be located will be described with reference to FIG.

  As shown in FIG. 5, in step 10, the mobile station 30 receives a control signal (pilot signal) from the serving cell and neighboring cells at an intermittent reception period (intermittent reception state).

  In step 20, the mobile station 30 detects the start of communication (outgoing / incoming). For example, the mobile station 30 detects the start of communication (incoming call) based on a control signal (paging display signal) received via the PICH.

  In step 30, the mobile station 30 continuously receives control signals (pilot signals) from the serving cell and the neighboring cells (continuous reception state).

  In step 40, the mobile station 30 evaluates the serving cell based on the reception quality of the control signal (common pilot signal) included in the status report transmitted via the RACH. Here, it should be noted that the process of step 40 is performed before the cell evaluation period elapses after the start of communication is detected.

  In step 50, the mobile station 30 determines whether or not the reception quality of the control signal (common pilot signal) included in the status report exceeds a predetermined threshold value. When the reception quality of the control signal (common pilot signal) exceeds the predetermined threshold (that is, when the evaluation result of the serving cell is good), the mobile station 30 proceeds to the process of step 60. On the other hand, when the reception quality of the control signal (common pilot signal) is equal to or lower than the predetermined threshold (that is, when the evaluation result of the serving cell is poor), the mobile station 30 performs the processing after step 90. Move on to (cell reselection process).

  In step 60, the mobile station 30 determines whether or not the cell evaluation period has expired. The mobile station 30 waits until the cell evaluation period expires, and then proceeds to the processing of step 70. The mobile station 30 sets the cell evaluation period in the cell evaluation period timer 33 when the process proceeds to step 70.

  In step 70, the mobile station 30 evaluates the serving cell and the neighboring cells based on the reception quality of the control signal (common pilot signal) continuously received during the cell evaluation period. Specifically, the mobile station 30 compares the reception quality of the control signal (pilot signal) received from the serving cell with the reception quality of the control signal (pilot signal) received from the neighboring cell.

  In step 80, the mobile station 30 determines whether or not to perform cell reselection processing based on the evaluation results of the serving cell and the neighboring cells. Specifically, when the reception quality of the control signal (pilot signal) received from the serving cell is degraded than the reception quality of the control signal (pilot signal) received from the neighboring cell, the mobile station 30 It is determined that cell reselection processing is performed.

  If the mobile station 30 determines to perform the cell reselection process, the mobile station 30 proceeds to the process of step 90. On the other hand, when the mobile station 30 determines not to perform the cell reselection process, the mobile station 30 returns to the process of step 60.

  In Step 90, the mobile station 30 receives broadcast information (a control signal transmitted via P-CCPCH) from the neighboring cells.

  In Step 100, the mobile station 30 determines whether or not to change the cell (located cell) where the mobile station should be located based on the reception result of the broadcast information.

  When the mobile station 30 changes the serving cell, the mobile station 30 proceeds to the process of step 110. In step 110, the mobile station 30 changes the serving cell by performing location registration and the like for the neighboring cells.

  On the other hand, when the mobile station 30 does not change the serving cell, the mobile station 30 proceeds to the process of step 120. In step 120, the mobile station 30 maintains the serving cell.

  In step 130, the mobile station 30 detects completion of the cell reselection process. Subsequently, the mobile station 30 returns to the process of step 60 described above.

  In the first embodiment, it should be noted that the processing from Step 90 to Step 130 is collectively referred to as cell reselection processing.

  Note that when the processing of step 110 and step 120 is completed, the mobile station 30 returns to the processing of step 60.

  Next, a process for establishing a dedicated channel for starting communication will be described with reference to FIG.

  As shown in FIG. 6, in step 200, the mobile station 30 detects the start of communication (outgoing / incoming) in the same manner as in step 20 described above.

  In step 210, the mobile station 30 determines whether or not the reception quality of the control signal (common pilot signal) included in the status report exceeds a predetermined threshold, as in step 50 described above. When the reception quality of the control signal (common pilot signal) exceeds a predetermined threshold, the mobile station 30 proceeds to the process of step 230. On the other hand, when the reception quality of the control signal (common pilot signal) is equal to or lower than the predetermined threshold, the mobile station 30 proceeds to the process of step 220.

  In step 220, the mobile station 30 determines whether or not the cell reselection process is completed. That is, the mobile station 30 waits until completion of the cell reselection process is detected in step 130, and then proceeds to the process of step 230.

  In Step 230, the mobile station 30 transmits a connection request (RRC CONNECTION REQUEST) to the serving cell.

  In Step 240, the mobile station 30 receives a connection setup (RRC CONNECTION SETUP) from the serving cell.

  In step 250, the mobile station 30 performs a dedicated channel (DPCH) establishment process for the serving cell.

(Function and effect)
According to the mobile station 30 according to the first embodiment, the cell evaluation unit 35A receives the control signal (common pilot signal) received from the serving cell before the cell evaluation period elapses after the start of communication is detected. It is determined whether the reception quality exceeds a predetermined threshold. Subsequently, when it is determined that the reception quality of the control signal (common pilot signal) is equal to or lower than the predetermined threshold, the cell evaluation unit 35A performs the cell reselection process without waiting for the cell evaluation period to elapse.

  That is, when the reception quality of the control signal (common pilot signal) received from the serving cell is deteriorated, the opportunity to perform the cell reselection process before the cell evaluation period elapses after the start of communication is detected. Is obtained. Therefore, it is possible to suppress the occurrence of a reconnection operation, communication disconnection, transmission delay, and the like due to an extended period (cell reselection period) for determining whether or not to perform cell reselection processing.

  Thus, when the mobile station 30 shifts from the intermittent reception state to the continuous reception state, the cell reselection cycle can be shortened.

  On the other hand, when it is determined that the reception quality of the control signal exceeds the predetermined threshold, the cell evaluation unit 35A waits for the cell evaluation period to elapse and continuously receives the control signal (common) within the cell evaluation period. A cell reselection process is performed according to a determination result based on reception quality of the pilot signal. Therefore, as in the past, it is possible to reduce the influence of temporary deterioration of the reception quality of the control signal due to fading or the like, and to select the optimum cell that the station should be in.

  According to the mobile station 30 according to the first embodiment, the communication processing unit 35B receives the control signal (common pilot signal) received from the serving cell before the cell evaluation period elapses after the start of communication is detected. If the quality is equal to or lower than the predetermined threshold, transmission of the connection request (RRC CONNECTION REQUEST) is stopped until the cell reselection process is completed.

  That is, when the serving cell is frequently changed, the transmission of the connection request is temporarily stopped. Therefore, it is possible to suppress the resending of the connection request due to the change of the serving cell after the connection request is transmitted.

  According to the mobile station 30 according to the first embodiment, the cell evaluation unit 35A diverts the reception quality included in the status report (Measurement result on RACH) when determining whether or not to perform the cell reselection process. Therefore, compared with the conventional mobile station 30, it is possible to shorten the cell reselection cycle without increasing the load on the mobile station 30.

[Other Embodiments]
Although the present invention has been described with reference to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the above-described embodiment, the cell evaluation process and the cell reselection process are performed on the mobile station 30 side, but are not limited thereto. Specifically, part or all of the cell evaluation process and the cell reselection process may be performed on the base station 10 side. In this case, it is needless to say that information necessary for the cell evaluation process and the cell reselection process may be notified from the mobile station 30 to the base station 10.

  In the above-described embodiment, the mobile station 30 transmits a connection request (RRC CONNECTION REQUEST) only when it is determined in step 220 that the cell reselection process has been completed, as shown in FIG. However, the present invention is not limited to this. Specifically, the mobile station 30 has a cell reselection timer that measures the time that has elapsed since the start of communication (incoming or outgoing) was detected. Here, if the time counted by the cell reselection timer exceeds a predetermined time, the mobile station 30 transmits a connection request (RRC CONNECTION REQUEST) even if the cell reselection process is not completed. .

In a prior art, it is a figure which shows the outline of the transfer from an intermittent reception state to a continuous reception state. It is a figure which shows the outline of the communication system which concerns on 1st Embodiment. It is a block diagram which shows the structure of the mobile station 30 which concerns on 1st Embodiment. In 1st Embodiment, it is a figure which shows the outline of the transfer from an intermittent reception state to a continuous reception state. It is a flowchart which shows the structure of the mobile station 30 which concerns on 1st Embodiment. It is a flowchart which shows the structure of the mobile station 30 which concerns on 1st Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Base station, 20 ... Cell, 30 ... Mobile station, 31 ... Reception part, 32 ... Intermittent reception period timer, 33 ... Cell evaluation period timer, 34 ... Reception Quality measurement unit, 35 ... control unit, 35A ... cell evaluation unit, 35B ... communication processing unit, 36 ... transmission unit

Claims (3)

Before the start of communication is detected, a control signal is received at intermittent reception cycles from the serving cell and the neighboring cell, and after the start of communication is detected, the control is performed from the serving cell and the neighboring cell. A receiver for continuously receiving signals;
Whether to perform a cell reselection process, which is a process of reselecting the serving cell, based on reception quality of the control signal received from the serving cell and the neighboring cell at the intermittent reception period 1 determination unit;
A second determination unit that determines whether or not to perform the cell reselection processing based on reception quality of the control signal continuously received from the serving cell and the neighboring cells within a cell evaluation period;
A third determination unit that determines whether reception quality of the control signal received from the serving cell exceeds a predetermined threshold before the cell evaluation period elapses after the start of the communication is detected;
A cell reselection processing unit that performs the cell reselection processing according to a determination result by the first determination unit, the second determination unit, or the third determination unit;
The cell reselection processing unit
If it is determined by the third determination unit that the reception quality of the control signal exceeds a predetermined threshold, the cell reselection is waited for the cell evaluation period to elapse and the cell reselection is performed according to the determination result by the second determination unit Process,
When the third determination unit determines that the reception quality of the control signal is a predetermined threshold or less, the mobile station performs the cell reselection processing without waiting for the cell evaluation period to elapse. . A transmission unit that transmits a connection request for requesting connection to the serving cell when the start of the communication is detected;
The transmission unit stops transmission of the connection request until the cell reselection process is completed when the third determination unit determines that the control signal is equal to or less than a predetermined threshold value. The mobile station according to claim 1. Before the start of communication is detected, a control signal is received at intermittent reception cycles from the serving cell and the neighboring cell, and after the start of communication is detected, the control is performed from the serving cell and the neighboring cell. In a communication system including a mobile station that continuously receives signals, the mobile station reselects the serving cell,
Determining whether or not to perform cell reselection processing, which is processing for reselecting the serving cell, based on reception quality of the control signal received from the serving cell and the neighboring cell at the intermittent reception period. A and
Step B for determining whether to perform the cell reselection process based on reception quality of the control signal continuously received from the serving cell and the neighboring cells within a cell evaluation period;
Determining whether the reception quality of the control signal received from the serving cell exceeds a predetermined threshold before the cell evaluation period elapses after the start of the communication is detected;
Step D for performing the cell reselection process according to the determination result of Step A, Step B or Step C,
In step D,
If the reception quality of the control signal exceeds a predetermined threshold value and is determined in step C, the cell reselection process is performed according to the determination result in step B after waiting for the cell evaluation period to elapse.
A communication method comprising: performing the cell reselection process without waiting for the cell evaluation period when it is determined in Step C that reception quality of the control signal is equal to or less than a predetermined threshold value.

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