JP2007150860A - Control station device and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform communication with low output in a zone to limit transmission power. <P>SOLUTION: A low output base station 102 constitutes a special cell 120 covering a zone to evade high output, and the low output base station 102 is different from a normal base station 101 on the point that the transmission power is limited. A control station 104 gives the communication with the low output base station 102 priority when a mobile station 103 is capable of the communication with both of the normal base station 101 and the low output base station 102, and also limits the transmission power of the low output base station 102 and the transmission power of the mobile station 103 which performs the communication with the low output base station 102 to the low output. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control station apparatus and a wireless communication method.

  It is said that high-power radio waves at short distances may adversely affect the operation of medical devices such as cardiac pacemakers. Use of mobile phones in places where medical devices are concentrated such as hospitals and nursing homes prohibited. However, it is troublesome to turn off the power of the mobile phone. Moreover, if the mobile phone is not turned off due to circumstances or carelessly forgotten, an accident involving human life may be caused.

  In preparation for such a case, there is a technique for stopping the transmission function itself of a mobile phone for a mobile phone that has entered an area where the use of the mobile phone is prohibited. However, being unable to transmit at all while in a hospital or nursing home for a long time is inconvenient for patients and their family members.

On the other hand, a repeater is provided between the base station and the mobile station, and this repeater communicates with the base station at a relatively high output, and is also a medical device with the mobile station. 2. Description of the Related Art A wireless communication system that performs communication with a low output that does not adversely affect is known (see, for example, Patent Document 1). In such a system, the repeater communicates with the base station using a directional antenna, and the mobile station communicates with the repeater preferentially over the base station. Therefore, according to this technique, the patient and the accompanying family can communicate with the outside without affecting the medical device.
JP 2003-283420 A

  However, since the repeater is a repeater with a simple function, there is a problem that if the number of users in the cover area increases to some extent, the communication quality deteriorates, sound is cut off, and the sound becomes unclear. In addition, this technology has a problem that it is necessary to newly install a repeater and to add a function to a mobile station.

  The present invention has been made in view of the above points, and in a medical facility or the like that wants to avoid high-power radio waves at a short distance, it is not necessary to install a new type of device, and safe and high-quality communication is performed. It is an object of the present invention to provide a control station apparatus and a wireless communication method that can be enabled.

  The control station apparatus of the present invention includes a first base station apparatus that manages a first cell, and a second base that manages a second cell that has a smaller cell radius than the first cell and is included in the first cell. A station apparatus, a mobile station apparatus that communicates with the first base station apparatus or the second base station apparatus, a control station that controls the first base station apparatus, the second base station apparatus, and the mobile station apparatus A control station device used in a wireless communication system comprising: the second base station when the mobile station device can communicate with both the first base station device and the second base station device. A priority unit that prioritizes communication between a station device and the mobile station device; and a setting unit that sets transmission power between the second base station device and the mobile station device to a predetermined upper limit value. Take.

  According to the present invention, even in a medical facility or the like that wants to avoid high-power radio waves at a short distance, it is possible to guarantee communication quality while enabling safe communication using an existing radio communication system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a configuration of a radio communication system 100 according to an embodiment of the present invention. Here, basically, a mobile communication system in which closed-loop transmission power control is performed will be described as an example.

  The communication area of the radio communication system 100 includes a normal cell 110 and a special cell 120 included in the normal cell 110. The special cell 120 covers an area where a medical facility such as the hospital 130 is installed, and the transmission power of the communication device in the special cell 120 is limited to a low output. The low output mentioned here is approximately the same as the maximum power of PHS, which is generally regarded as having no adverse effect on medical devices, and a maximum number of 10 [mW].

  The wireless communication system 100 includes a normal base station 101, a low power base station 102, a mobile station 103-1, a mobile station 103-2, and a control station 104. The mobile station 103-1 and the mobile station 103-2 are mobile stations having the same configuration, and in the following description, when they are described collectively, the branch numbers are omitted.

  The normal base station 101 configures the normal cell 110 and communicates with the mobile station 103-1 with normal transmission power.

  The low output base station 102 has the same function as that of the base station 101 except that the transmission power is limited to a low output that does not adversely affect medical devices, cardiac pacemakers, and the like. Since the special cell 120 is included in the normal cell 110, diversity reception is avoided by making the frequency used by the low-power base station 102 different from the frequency used by the normal base station 101.

  The mobile station 103-1 communicates with the normal base station 101 configuring the normal cell 110 with normal transmission power. Hereinafter, the case where the mobile station 103 communicates with the normal base station 101 configuring the normal cell 110 is referred to as the mobile station 103 residing in the normal cell 110.

  The mobile station 103-2 communicates with the low-power base station 102 configuring the special cell 120 at a low power that does not adversely affect medical devices, cardiac pacemakers, and the like. Hereinafter, the case where the mobile station 103 communicates with the low-power base station 102 configuring the special cell 120 is referred to as the mobile station 103 residing in the special cell 120.

  The control station 104 controls the normal base station 101, the low-power base station 102, and the mobile station 103 in the wireless communication system 100.

  FIG. 2 is a block diagram showing a configuration of control station 104 according to the present embodiment.

  The mobile station location information storage unit 201 stores information on which base station the mobile station 103 in the cover area of the control station 104 is communicating with, and outputs this information to the different frequency handover determination unit 206.

  The cell type identification unit 202 identifies whether the cell in the cover area of the control station 104 is the normal cell 110 or the special cell 120, and outputs the identification result to the cell type information storage unit 203 and the downlink transmission power upper limit selection unit 214.

  The cell type information storage unit 203 stores the cell type information identified by the cell type identification unit 202, and outputs this information to the frequency allocation unit 204 and the different frequency handover determination unit 206.

  The frequency allocation unit 204 is connected to the normal base station 101 and the low-power base station 102 based on the cell type information stored in the cell type information storage unit 203 so as to avoid diversity reception between the normal base station 101 and the low-power base station 102. A different frequency is assigned to the output base station 102. The normal base station 101 and the low power base station 102 communicate with the mobile station 103 using the frequency notified from the frequency allocation unit 204.

  The compressed mode activation unit 205 performs normal cell search and handover so that the mobile station 103 can perform cell search and perform handover even when the mobile station 103 is communicating with the normal base station 101 (during a call or data communication). A compressed mode is activated for each individual mobile station communication with the base station 101. Similarly, the compressed mode activation unit 205 performs a cell search and a handover even when the mobile station 103 is communicating with the low power base station 102, so that the mobile station 103 and the low power base station 102 can perform a handover. Activates compressed mode for communication with Normally, since the mobile station 103 performs wireless communication with one synthesizer during communication, a different frequency cell search cannot be performed. The compressed mode is a function that enables different frequency cell search and different frequency handover of the mobile station 103 in communication. The compressed mode activation unit 205 instructs the mobile station 103 to activate the compressed mode, and the mobile station 103 that has received this instruction performs a different frequency cell search while switching the synthesizer in a slot called a transmission gap.

  The different frequency handover determination unit 206 determines the different frequency handover according to an algorithm for prioritizing communication with the special cell 120 over the normal cell 110. Since the special cell 120 and the normal cell 110 use different frequencies, the handover between the special cell 120 and the normal cell 110 is abbreviated as a different frequency handover here, and the cell search performed for the different frequency handover is different. This is abbreviated as frequency cell search. The different frequency handover determination unit 206 instructs the compressed mode activation unit 205 to activate the compressed mode during the determination process. The different frequency handover determination unit 206 outputs the determination result to the uplink transmission power upper limit selection unit 212 and instructs the mobile station 103 to perform the different frequency handover. Details of the determination processing in the different frequency handover determination unit 206 will be described later.

  The handover threshold storage unit 207 is a threshold for determining whether or not the communication quality between the mobile station 103 and the low power base station 102 deteriorates and the mobile station 103 needs to perform a different frequency handover to the normal cell 110. And outputs this threshold value to the different frequency handover determination unit 206.

  The communication quality report value storage unit 208 stores values such as CPICH Ec / NO, CPICH RSCP, and path loss indicating the communication quality, and outputs them to the communication quality report value comparison unit 209. These values indicate communication quality between the mobile station 103 and the base station measured by the mobile station 103 by performing a cell search, and may be hereinafter referred to as cell communication quality. The mobile station 103 reports these measured values to the control station 104 using a measurement report.

  The communication quality report value comparison unit 209 includes a communication quality report value (latest value) acquired by the control station 104 from the mobile station 103, and a communication quality report value (past value) stored in the communication quality report value storage unit 208. Compare Hereinafter, when the communication quality of a cell deteriorates, the latest value of the communication quality report value becomes smaller than the past value. The communication quality report value comparison unit 209 outputs the comparison result to the different frequency handover determination unit 206.

  The cell validity determination threshold value storage unit 210 stores a communication quality threshold value for determining that a cell is valid, and outputs the threshold value to the different frequency handover determination unit 206. The different frequency handover determination unit 206 compares the communication quality of the cell with this threshold value to determine whether or not the base station constituting this cell can communicate with the mobile station 103 that is handed over from another cell. judge.

  The upper limit of the uplink transmission power stored in the uplink transmission power upper limit storage unit 211 is, for example, several tens [mW]. This upper limit is an upper limit of the special cell uplink transmission power in the mobile station 103 when communicating with the low-power base station 102. The uplink transmission power upper limit storage unit 211 outputs the upper limit of the special cell uplink transmission power to the uplink transmission power upper limit selection unit 212.

  Uplink transmission power upper limit selection section 212 has an upper limit setting value for uplink transmission power that differs between when mobile station 103 communicates with normal base station 101 and when mobile station 103 communicates with low-power base station 103. Select a value. More specifically, when the mobile station 103 communicates with the low-power base station 102, the uplink transmission power upper limit selection unit 212 selects the upper limit of the special cell uplink transmission power stored in the uplink transmission power upper limit storage unit 211. Then, the mobile station 103 is instructed. When mobile station 103 communicates with normal base station 101, uplink transmission power upper limit selection section 212 selects the upper limit of transmission power in normal uplink transmission power control and instructs mobile station 103.

  The upper limit of the downlink transmission power stored in the downlink transmission power upper limit storage unit 213 is, for example, several tens [mW], and this upper limit is the upper limit of the special cell downlink transmission power. The downlink transmission power upper limit storage section 213 outputs the upper limit of the special cell downlink transmission power to the downlink transmission power upper limit selection section 214.

  The downlink transmission power upper limit selection unit 214 selects different values for the normal base station 101 and the low-power base station 103 as the upper limit setting value of the downlink transmission power, and instructs each base station. More specifically, the downlink transmission power upper limit selection unit 214 sets the upper limit of the downlink transmission power for special cells stored in the downlink transmission power upper limit storage unit 213 for the low-power base station 102, and sets the low output Instructs the base station 102. Further, the downlink transmission power upper limit selection unit 214 sets an upper limit of transmission power in normal downlink transmission power control for the normal base station 101 and instructs the normal base station 101.

  FIG. 3 is a flowchart showing an algorithm in which the control station 104 shown in FIG.

  In step (ST) 3010, the different frequency handover determination unit 206 is based on the information stored in the mobile station location information storage unit 201 and the cell type information storage unit 203, and the serving cell of the mobile station is a special cell. Determine whether or not.

  In ST3010, when it is determined that the serving cell of the mobile station is not a special cell (ST3010: NO), in ST3020, the different frequency handover determination unit 206 determines whether the mobile station location information storage unit 201 and the cell type information storage unit 203 Based on the stored information, it is determined whether or not a special cell exists around the mobile station's serving cell. When there is a special cell around the serving cell, the special cell is included in the normal cell where the mobile station is located, or it is adjacent to the normal cell where the mobile station is located One of the cases where the special cell is included in the normal cell.

  In ST3020, when it is determined that there is no special cell around the cell in which the mobile station is located (ST3020: NO), the different frequency handover determination unit 206 repeats the above determination with a predetermined time interval.

  In ST3020, when it is determined that there is a special cell in the vicinity of the serving cell of the mobile station (ST3020: YES), in ST3030, the different frequency handover determination unit 206 issues an instruction to the compressed mode activation unit 205 to move The compressed mode is activated for communication of each mobile station performed between the station and the normal base station, and the mobile station performs a different frequency cell search.

  In ST3040, different frequency handover determining section 206 acquires values such as CPICH Ec / NO, CPISCP, and path loss measured by the mobile station by performing different frequency cell search in a measurement report.

  In ST3050, different frequency handover determining section 206 compares the communication quality of the special cell reported in the measurement report from the mobile station with the cell effective determination threshold stored in cell effective determination threshold storage section 210, and It is determined whether or not is valid.

  In ST3050, when it is determined that the special cell is not valid (ST3050: NO), the different frequency handover determination unit 206 returns to ST3040 and acquires a measurement report from the mobile station again.

  In ST3050, when it is determined that the special cell is valid (ST3050: YES), the different frequency handover determining unit 206 determines that the mobile station is to perform the different frequency handover to the special cell. That is, the different frequency handover determination unit 206 determines whether or not the communication quality of the special cell exceeds the standard with reference to the threshold value stored in the cell validity determination threshold value storage unit 210. Regardless, it decides to hand over the mobile station to a special cell.

  In ST 3060, uplink transmission power upper limit selection section 212 sets the upper limit of the uplink transmission power of the mobile station performing the different frequency handover using the upper limit of the special cell uplink transmission power based on the determination result of different frequency handover determination section 206. To do. Then, the mobile station performs a different frequency handover to the special cell, and communicates with the low-power base station 102 at a low power.

  When it is determined in ST3010 that the cell in which the mobile station is located is a special cell (ST3010: YES), in ST3070, the different frequency handover determination unit 206 determines that the mobile station is at the start timing of the different frequency cell search. Determine whether or not.

  In ST3070, when it is determined that the mobile station is not at the start timing of the different frequency cell search (ST3070: NO), the different frequency handover determination unit 206 repeats the above determination with a predetermined time interval.

  When it is determined in ST3070 that the mobile station is at the start timing of the different frequency cell search (ST3070: YES), in ST3080, the compressed mode activation unit 205 is performed between the mobile station and the low-power base station. The compressed mode is activated for each mobile station's individual communication, and the mobile station performs cell search.

  In ST3090, different frequency handover determination section 206 initializes past communication quality report values stored in communication quality report value storage section 208 to zero.

  In ST3100, the different frequency handover determination section 206 clears the count parameters “temporary determination count” and “deterioration detection count” and initializes them to zero. Details of the provisional determination count and the deterioration detection count will be described later.

  In ST3110, different frequency handover determination section 206 acquires the communication quality between the special cell and the normal cell from the mobile station using the latest measurement report.

  In ST3120, different frequency handover determination section 206 performs the latest (previous) stored in communication quality report value storage section 208 with the latest report value related to the communication quality of the special cell performed in communication quality report value comparison section 209. Whether or not the communication quality of the special cell has deteriorated is determined based on the comparison result with the reported value.

  If it is determined in ST3120 that the communication quality has not deteriorated (ST3120: NO), in ST3210, different frequency handover determination section 206 clears the number of times of deterioration detection to zero.

  In ST3220, different frequency handover determination section 206 stores the latest report value related to the communication quality between the special cell and the normal cell in communication quality report value storage section 208 so that it can be used later as a past report value.

  In ST3230, the different frequency handover determination section 206 determines whether or not the individual communication for each mobile station being performed between the mobile station and the low power base station is in the compressed mode. When it is determined in ST3230 that the compressed mode is selected (ST3230: YES), the different frequency handover determination unit 206 returns to ST3110 and acquires the latest measurement report from the mobile station again. If it is determined in ST3230 that the compressed mode is not selected (ST3230: NO), different frequency handover determination section 206 returns the process to ST3070.

  When it is determined in ST3120 that the communication quality is deteriorated (ST3120: YES), in ST3130, the different frequency handover determination unit 206 increments the number of times of deterioration detection by one. One of the determination conditions used by the different frequency handover determination unit 206 in the determination process of the different frequency handover is whether or not the number of times the deterioration of the communication quality of the special cell has been reached a predetermined number. The “deterioration detection count” is a counter that counts the number of times communication quality deterioration has been detected.

  In ST3140, different frequency handover determination section 206 determines whether or not the number of deterioration detections has reached a predetermined number.

  If it is determined in ST3140 that the number of deterioration detections has not reached the predetermined number (ST3140: NO), different frequency handover determination section 206 advances the process to ST3220.

  When it is determined in ST3140 that the number of times of deterioration detection has reached a predetermined number (ST3140: YES), in ST3150, the different frequency handover determination unit 206 determines that the communication quality of the special cell is stored in the handover threshold storage unit 207 It is determined whether or not:

  If it is determined in ST3150 that it is not less than or equal to the handover threshold (ST3150: NO), in ST3200, different frequency handover determination section 206 clears the tentative determination count to 0 and advances the process to ST3220.

  When it is determined in ST3150 that it is equal to or lower than the handover threshold (ST3150: YES), in ST3160, the different frequency handover determination unit 206 determines the communication quality of the normal cell and the threshold stored in the cell validity determination threshold storage unit 210. In comparison, it is determined whether or not the normal cell is valid.

  If it is determined in ST3160 that the normal cell is not valid (ST3160: NO), different frequency handover determining section 206 advances the process to ST3200.

  If it is determined in ST3160 that the normal cell is valid (ST3160: YES), in ST3170, the different frequency handover determining unit 206 provisionally determines to perform the different frequency handover, and increments the number of temporary determinations by one. The inter-frequency handover tentative decision means a case where the number of times of deterioration detection reaches a predetermined number (ST3140), and further, both the handover threshold determination condition (ST3150) and the normal cell validity determination condition (ST3160) are satisfied. . The “temporary decision count” is a counter that counts the number of times of the tentative decision of the different frequency handover, and the different frequency handover determination unit 206 actually performs the different frequency handover when the tentative decision count reaches a predetermined number. To decide.

  In ST3180, different frequency handover determination section 206 determines whether or not the number of provisional determinations has reached a predetermined number.

  If it is determined in ST3180 that the number of provisional decisions has not reached the predetermined number (ST3180: NO), different frequency handover determination section 206 advances the process to ST3220.

  In ST3180, when it is determined that the number of provisional determinations has reached the predetermined number (ST3180: YES), different frequency handover determining section 206 determines to cause the mobile station to perform different frequency handover to the normal cell.

  In ST3190, uplink transmission power upper limit selection section 212 sets an upper limit of normal uplink transmission power control for the mobile station that performs the different frequency handover based on the determination result of different frequency handover determination section 206. Then, the mobile station performs a different frequency handover to the normal cell and communicates with the normal base station with normal transmission power.

  4 to 6 are diagrams for explaining the determination process of the control station 104 for handing over the mobile station 103 from the normal cell 110 to the special cell 120 using the algorithm of FIG.

  FIG. 4 is a diagram illustrating a determination example for the control station 104 to hand over the mobile station 103 from the normal cell 110 to the special cell 120 at a different frequency. The components in this figure are basically the same as those in FIG. 1, and thus detailed description of each component is omitted. Compared with FIG. 1, this figure shows in more detail the route that the mobile station 103 moves from point A to point C via point B. That is, in this figure, the mobile station 103 gradually approaches the special cell 120 as it moves.

  FIG. 5 is a diagram illustrating information stored in the control station 104 when the mobile station 103 is located at the point A. Among the stored information, the control station 104 stores cell type information for distinguishing the normal cell 110 configured by the normal base station 101 and the special cell 120 configured by the low-power base station 102 from the cell type information storage unit 203. And the location registration information of the mobile station 103 is stored in the mobile station location information storage unit 201.

  FIG. 6 is a diagram showing CPICH Ec / N0 values measured by the mobile station 103 performing cell search at points A, B, and C. In this example, the control station 104 determines the different frequency handover using the CPICH Ec / NO value as a measured value indicating the communication quality of the cell. This figure shows the relative relationship between the CPICH Ec / N0 value of each of the normal cell 110 and the special cell 120 and the cell validity determination threshold value. In this figure, N indicates a normal cell 110 and S indicates a special cell 120. As shown in this figure, when the mobile station 103 is located at points A and B, the normal cell 110 is valid, but the special cell 120 is not valid. On the other hand, when the mobile station 103 is located at the point C, both the normal cell 110 and the special cell 120 are effective. As shown in the figure, at the point C, the communication quality of the special cell 120 is lower than the communication quality of the normal cell 110 but is effective, so the control station 104 decides to hand over the mobile station 103 to the special cell 120 at a different frequency. .

  In FIG. 4, based on the information shown in FIG. 5, the control station 104 determines that the mobile station 103 communicates with the normal base station 101 at the point A (ST3010: NO) and the special cell 120 exists in the vicinity. (ST3020: YES). Therefore, the control station 104 activates the compressed mode for the individual communication of the mobile station 103 performed between the mobile station 103 and the normal base station 101 (ST3030). When the compressed mode is activated, the mobile station 103 performs a cell search and measures the CPICH Ec / N0, CPICH RSCP, path loss, etc. of the special cell 120. The mobile station 103 puts these measurement values on the measurement report and reports them to the control station 104 via the normal base station 101 (ST3040). Based on the measurement report acquired from mobile station 103, control station 104 determines that special cell 120 is not valid as shown in FIG. 6 (ST3050: NO). Unless special cell 120 is valid (for example, when mobile station 103 is located at point B), control station 104 repeatedly obtains a measurement report from mobile station 103 (ST3040), and determines the validity of special cell 120. (ST3050). When the mobile station 103 is located at the point C, the control station 104 determines that the special cell 120 is valid as shown in FIG. 6 (ST3050: YES), and hands over the mobile station 103 to the special cell 120 (ST3060). ) The mobile station 103 communicates with the low-power base station 102 with transmission power that does not adversely affect the medical device.

  FIGS. 7 to 9 are diagrams for explaining the determination process of the control station 104 for handing over the mobile station 103 from the special cell 120 to the normal cell 110 using the algorithm of FIG.

  FIG. 7 is a diagram illustrating a determination example for the control station 104 to hand over the mobile station 103 from the special cell 120 to the normal cell 110 in a different frequency. This figure is an enlarged view of the special cell 120 shown in FIG. 1 and its surroundings, and since each component is the same as that in FIG. 1, its detailed description is omitted. Compared with FIG. 1, this figure shows in more detail the route that the mobile station 103 moves from point C to point A via point B. That is, in this figure, the mobile station 103 gradually moves away from the special cell 120 as it moves, unlike the case shown in FIG.

  FIG. 8 is a diagram illustrating information stored in the control station 104 when the mobile station 103 is located at the point C. The control station 104 stores cell type information for distinguishing the normal cell 110 configured by the normal base station 101 and the special cell 120 configured by the low-power base station 102 among the stored information. 203, and the location registration information of the mobile station 103 is stored in the mobile station location information storage unit 201.

  FIG. 9 is a diagram showing CPICH Ec / N0 values measured by the mobile station 103 performing cell search at points A, B, and C. In this example, the control station 104 determines the different frequency handover using the CPICH Ec / NO value as a measured value indicating the communication quality of the cell. This figure shows the relative relationship between the CPICH Ec / N0 value of the normal cell 110, the CPICH Ec / N0 value of the special cell 120, the cell validity determination threshold value, and the handover threshold value. As shown in this figure, the control station 104 sets the handover threshold lower than the cell validity determination threshold. In this figure, N indicates a normal cell 110 and S indicates a special cell 120. As shown in the figure, when the mobile station 103 is located at the point C, both the normal cell 110 and the special cell 120 are effective. When the mobile station 103 is located at the point B, the normal cell 110 is valid and the special cell 120 is not valid, but the communication quality of the special cell 120 is equal to or higher than the handover threshold. When the mobile station 103 is located at the point A, the normal cell 110 is valid, the special cell 120 is not valid, and the communication quality of the special cell 120 is below the handover threshold. The control station 104 maintains communication between the mobile station 103 and the low-power base station 102 as long as the communication quality of the special cell 120 does not fall below the handover threshold.

  In FIG. 7, the control station 104 determines that the mobile station 103 communicates with the low-power base station 102 at the point C based on information as shown in FIG. 8 (ST3010: YES). Therefore, the control station 104 responds to individual communication of the mobile station 103 performed between the mobile station 103 and the low power base station 102 at the start timing of the different frequency cell search of the mobile station 103 (ST3070: YES). Then, the compressed mode is activated (ST3080). Next, the control station 104 initializes the past report value, the number of times of deterioration detection, and the number of provisional determinations regarding the communication quality to 0 (ST3090, ST3100). The mobile station 103 performs a cell search and measures CPICH Ec / N0, CPICH RSCP, path loss, etc. of the normal cell 110 and the special cell 120, respectively. The mobile station 103 puts these measurement values on the measurement report, and reports them to the control station 104 via the low-power base station 102 (ST3110). Based on this report value acquired from mobile station 103, control station 104 determines that the communication quality of special cell 120 has not deteriorated (ST3120: NO). Therefore, the control station 104 initializes the number of times of deterioration detection to 0 (ST3210), and stores the communication quality report value so that the communication quality report value reported when the mobile station 103 is at the point C is used later as the past value. Stored in unit 208 (ST3220). Next, the control station 104 determines that the individual communication of the mobile station 103 being performed between the mobile station 103 and the low-power base station 102 is in the compressed mode (ST3230: YES), and again determines the measurement report. Acquisition is performed (ST3110).

  When the mobile station 103 moves to the point B, the control station 104 determines that the communication quality of the special cell has deteriorated based on the latest measurement report obtained from the mobile station 103 (ST3110) (ST3120: YES), The degradation detection count is incremented by 1 (ST3130). As a result, the number of degradation detections has reached the threshold at point B (ST3140: YES), but the control station 104 determines that the communication quality of the special cell 120 has not degraded to the handover threshold or less as shown in FIG. Determine (ST3150: NO). Therefore, control station 104 clears the tentative determination count to 0 (ST3200). Further, the control station 104 stores the communication quality report value reported when the mobile station 103 is at the point B in the communication quality report value storage unit 208 for later use as a past value (ST3220). The measurement report is acquired again (ST3110).

  When the mobile station 103 moves to the point A, the processing of ST3110 to ST3140 in FIG. 3 in the control station 104 is the same as when the mobile station 103 is located at the point B. Next, as shown in FIG. 9, when the mobile station 103 moves to the point A as shown in FIG. 9, the communication quality of the special cell is equal to or lower than the handover threshold (ST3150: YES), and the control quality of the normal cell 110 is effective. It is determined that there is (ST3160: YES), and the provisional determination count is incremented by 1 (ST3170). As a result, since the number of provisional decisions reaches a predetermined number (ST3180: YES), the control station 104 hands over the mobile station 103 to the normal cell 110 in a different frequency (ST3190) and communicates with the normal base station 101 with normal output. To do. In this case, since the mobile station 103 is already sufficiently separated from the special cell 120, the mobile station 103 does not adversely affect the medical device located in the special cell 120.

  Thus, according to the present embodiment, when a special cell exists around a normal cell where the mobile station is located, the control station performs each operation performed between the mobile station and the normal base station. The compressed mode is activated for communication of each mobile station, and the mobile station performs a different frequency cell search. In such a case, the control station hands over the mobile station to the special cell as long as the special cell is valid regardless of the communication quality of the normal cell. For this reason, priority can be given to communication between a low-power base station and a mobile station over a normal base station. When the mobile station is located in a special cell, the mobile station located in the special cell is set to a low power base by setting the cell validity determination threshold higher than the handover threshold from the special cell to the normal cell. As long as the communication with the station can be continued, the communication can be maintained as much as possible. In addition, the low-power base station is a device having the same function with the same configuration as the normal base station, only by limiting the transmission power of the normal base station, so without installing a new type of device separately, Safe and good quality mobile communication in a medical facility or the like can be realized using an existing wireless communication system.

  In addition, according to the present embodiment, the priority of communication between the mobile station and the low-power base station, that is, the medical service, is changed by changing the predetermined number of times of deterioration detection of the control station and the predetermined number of times of provisional frequency determination The safety level of mobile communication in a facility or the like can be adjusted as necessary.

  In the present embodiment, different frequencies are used for the normal base station and the low-power base station, but spread codes that are orthogonal to each other may be used according to the communication method.

  In addition, although the present embodiment describes the handover process of a mobile station in communication, when the mobile station performs an initial cell search when the power is turned from OFF to ON, or when performing a cell search during standby However, as long as there is an effective special cell regardless of the communication quality of the normal cell, the special cell may be randomly accessed. Thereby, the priority of communication between the mobile station and the low-power base station can be further improved, and the safety of mobile communication in a medical facility or the like can be further improved.

  In addition, when the mobile station makes a call or when the mobile station is notified of an incoming call, the control station may cause the mobile station to perform a different frequency cell search before the mobile station performs the outgoing call process or the incoming call process. good. In such a case, as long as there is a valid special cell regardless of the communication quality of the normal cell, the mobile station re-registers the location in the special cell and then performs outgoing call processing or incoming call processing. As a result, when the cell search execution cycle is long, the mobile station is prevented from moving to the special cell during the period when the cell search operation is paused and communicating with the normal base station with normal power in the special cell. Can do. That is, it is possible to further improve the priority of communication between the mobile station and the low-power base station and the safety of mobile communication in a medical facility.

  In this embodiment, a medical facility is described as an example. However, the present invention can be applied to other areas where high frequency and high output radio waves are desired to be avoided.

  Further, here, the case where the present invention is configured by hardware has been described as an example, but the present invention can also be realized by software. For example, an algorithm for different frequency handover determination processing according to the present invention can be described in a programming language, and the program can be stored in a memory and executed by information processing means.

  The present invention can provide safe and high-quality wireless communication in an area where transmission power is desired to be limited, and thus is suitable for use in medical facilities and the like.

The figure which shows the structure of the radio | wireless communications system which concerns on one embodiment of this invention The figure which shows the structure of the control station which concerns on one embodiment of this invention The flowchart which shows the algorithm in which the control station which concerns on one embodiment of this invention performs the determination of different frequency handover with respect to a mobile station The figure which shows the example of a determination for the control station which concerns on one embodiment of this invention to perform a different frequency handover of a mobile station from a normal cell to a special cell The figure which shows the information which the control station memorize | stores when the mobile station which concerns on one embodiment of this invention is in A point The figure which shows CPICH Ec / N0 value which the mobile station which concerns on one embodiment of this invention measured by performing a cell search in each point of A, B, and C The figure which shows the example of determination for the control station which concerns on one embodiment of this invention to perform a different frequency handover from a special cell to a normal cell The figure which shows the information which the control station memorize | stores when the mobile station which concerns on one embodiment of this invention is in C point The figure which shows CPICH Ec / N0 value which the mobile station which concerns on one embodiment of this invention measured by performing a cell search in each point of A, B, and C

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Wireless communication system 101 Normal base station 102 Low-power base station 103-1, 103-2 Mobile station 104 Control station 110 Normal cell 120 Special cell 201 Mobile station location information storage unit 202 Cell type identification unit 203 Cell type information storage unit 204 Frequency allocation unit 205 Compressed mode activation unit 206 Different frequency handover determination unit 207 Handover threshold storage unit 208 Communication quality report value storage unit 209 Communication quality report value comparison unit 210 Cell validity determination threshold storage unit 211 Uplink transmission power upper limit storage unit 212 Uplink Transmission power upper limit selection unit 213 Downlink transmission power upper limit storage unit 214 Downlink transmission power upper limit selection unit

Claims (5)

A first base station device that manages the first cell;
A second base station device having a cell radius smaller than that of the first cell and managing a second cell included in the first cell;
A mobile station apparatus that communicates with the first base station apparatus or the second base station apparatus;
A control station apparatus that controls the first base station apparatus, the second base station apparatus, and the mobile station apparatus;
A control station apparatus used in a wireless communication system comprising:
When the mobile station device can communicate with both the first base station device and the second base station device, priority means for prioritizing communication between the second base station device and the mobile station device;
Setting means for setting transmission power between the second base station apparatus and the mobile station apparatus to a predetermined upper limit;
A control station apparatus comprising: The priority means allows the second base station apparatus and the mobile station apparatus to communicate with a communication quality equal to or higher than a predetermined value regardless of the communication quality between the first base station apparatus and the mobile station apparatus. If so, the mobile station apparatus is handed over to the second cell.
The control station apparatus according to claim 1. As long as the communication quality between the second base station apparatus and the mobile station apparatus does not become a predetermined value or less, regardless of the communication quality between the first base station apparatus and the mobile station apparatus. , Maintaining communication between the second base station device and the mobile station device,
The control station apparatus according to claim 1. The priority means allows the second base station apparatus and the mobile station apparatus to communicate with a communication quality equal to or higher than a predetermined value regardless of the communication quality between the first base station apparatus and the mobile station apparatus. If so, let the mobile station apparatus perform the outgoing call process or the incoming call process after registering the location of the mobile station apparatus in the second cell,
The control station apparatus according to claim 1. A first cell managed by the first base station apparatus;
A radio communication method in a radio communication system configured by a second cell managed by a second base station apparatus whose transmission power is restricted and which is included in the first cell and has a cell radius smaller than that of the first cell Because
Regardless of the communication quality between the first base station apparatus and the mobile station apparatus, if the second base station apparatus and the mobile station apparatus can communicate with a communication quality of a predetermined value or more, the mobile While the station device is handed over to the second cell, communication between the second base station device and the mobile station device is performed as long as communication quality between the second base station device and the mobile station device does not become a predetermined value or less. A wireless communication method to be maintained.

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