JP2939114B2 - Mobile communication handover method, mobile station apparatus and base station apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a code division multiple access (hereinafter abbreviated as CDMA) using a spread spectrum code.
TECHNICAL FIELD The present invention relates to a mobile communication handover method, a mobile station apparatus, and a base station apparatus in a mobile communication system of a system.

[0002]

2. Description of the Related Art In a CDMA mobile communication system using spread spectrum codes, a service area is divided into a plurality of unit areas, cells, and one base station is provided in each cell. A mobile station existing in a certain cell communicates with a base station of the cell via a radio line, and communicates with another mobile station or a telephone or the like from the base station via another radio line or a communication line. It has become.

In a CDMA mobile communication system, the base stations of each cell are assigned different unique spreading codes of the same frequency, spread with the spreading codes, and stop at a fixed transmission power without performing transmission power control. The tree channel is constantly transmitted. For example, as shown in FIG. 5, a plurality of cells 1, 1 provided in a service area
2, 3,... Respectively have base stations B1, B2, B3,
Are provided, and each base station B1, B2, B3,.
Have different spreading codes C1, C2, C3,.
Is assigned. Then, the base station of each cell always transmits the perch channel spread with the assigned spreading code.

As shown in FIG. 5, a mobile station M1 communicating with the base station B1 via the radio line 91 in the cell 1 moves in the direction shown by the arrow 92 to another cell. In the case of moving within 2 or 3, the mobile station M1
Since the communication level with the base station B1 during communication gradually decreases, the mobile station M1 performs communication with the base station B1 in cell 2
It is necessary to switch to communication with the base station B2 of the cell 3, the base station B3 of the cell 3, and the like.

Therefore, in order to perform such switching, that is, handover, in a conventional system,
The mobile station receives the spreading code of the neighboring cell from the communicating base station, sequentially scans the reception level of the pilot channel or the perch channel spread with the spreading code,
A cell whose reception level is equal to or higher than a predetermined threshold is selected, a communication channel of the selected cell is newly connected, and a simultaneous communication mode is established with the base station of the cell,
The reception level from the cell currently communicating is measured, and when the reception level falls below a predetermined low threshold value, an operation of disconnecting the communication line with the cell is performed.

[0006]

In the above-described conventional method, a cell whose reception level is simply higher than a predetermined threshold value is selected from neighboring cells. A cell requiring a relatively large communication channel transmission power may be selected, and performing communication with a cell requiring such a relatively large communication channel transmission power may interfere with communication with other cells. There is a problem.

In the process of connecting cells having a reception level equal to or higher than a predetermined threshold value and disconnecting the cells when the reception level drops below a predetermined low threshold value, many cells overlap each other. In an area where cell connection and disconnection, that is, handover flutter occurs relatively frequently, control for this becomes difficult,
There is a problem that the load on the control device increases.

[0008] The present invention has been made in view of the above,
The objective is to reduce the transmission power, reduce the interference power, increase the subscriber capacity, and suppress the handover flutter to reduce the control load and the mobile communication handover method and mobile station apparatus. An object of the present invention is to provide a base station device.

[0009]

In order to achieve the above object, a mobile communication handover method according to the present invention provides a base station in each of a plurality of cells, each base station being modulated at the same frequency and different from each other. A mobile communication handover method in a code division multiple access mobile communication system which constantly transmits a perch channel having a constant transmission power which is spread with an assigned unique spreading code and does not perform transmission power control, comprising: Measures the reception level of each perch channel of the neighboring cell during communication, and determines a first level difference between a reception level exceeding a first predetermined reception level and a maximum reception level during communication among the reception levels. A cell having a reception level smaller than the predetermined level difference is newly connected to the mobile station to enter the simultaneous communication mode, and a plurality of cells in the mobile station performing simultaneous communication are connected. If the level difference between each of the received signal levels and the maximum received level among the received levels is larger than a second predetermined level difference that is larger than the first predetermined level difference, or reception during simultaneous communication is performed. When the level is lower than a second predetermined reception level which is lower than the first predetermined reception level, the gist of the present invention is to disconnect the line for the cell.

In the mobile communication handover method according to the present invention, in the step of measuring the reception level, a spreading code of a neighboring cell is notified from a base station with which communication is currently being performed,
The gist is to measure the reception level of each perch channel of the neighboring cells using the notified spreading code.

Further, in the mobile station apparatus of the present invention, a base station is provided in each of a plurality of cells, each base station is modulated at the same frequency, spread with a unique spreading code assigned differently, and transmitted. A mobile station device in a mobile communication system of a code division multiple access system that constantly transmits a perch channel having a constant transmission power without performing power control,
Measuring means for measuring the reception level of each perch channel of the peripheral cell during communication, among the reception levels measured by the measurement means, a reception level exceeding a first predetermined reception level and a maximum reception level during communication Detecting means for detecting a cell having a reception level having a level difference smaller than a first predetermined level difference between each of the plurality of cells during simultaneous communication, and a maximum of the reception levels. A cell whose level difference from the reception level is larger than the second predetermined level difference is larger than the second predetermined level difference, or the reception level during simultaneous communication is smaller than the first predetermined reception level. The present invention has a second detecting means for detecting a cell which has become lower than a second predetermined reception level.

[0012] In the mobile station apparatus of the present invention, as the measuring means, a spreading code of a neighboring cell is notified from a base station with which communication is currently being performed, and using the notified spreading code, the perch channel of each of the neighboring cells is used. The gist of the invention is to have means for measuring the reception level.

Further, the mobile station apparatus of the present invention further comprises simultaneous communication means for newly connecting a cell detected by the first detection means to enter a simultaneous communication mode with the cell.

Further, the mobile station apparatus according to the present invention further comprises a notifying means for notifying the cell detected by the first detecting means to the base station, and the base station receiving the notification newly adds the cell. The gist of the present invention is to perform control to connect to a mobile station and enter a simultaneous communication mode with the cell.

The gist of the present invention is that the mobile station apparatus further comprises a disconnecting means for disconnecting a line to the cell detected by the second detecting means.

Further, the mobile station apparatus of the present invention further comprises communication means for notifying the cell detected by the second detection means to the base station, and the base station receiving the notification sets a line for the cell. The gist is to control the cutting.

In the base station apparatus of the present invention, a base station is provided in each of a plurality of cells, each base station is modulated at the same frequency, spread with a unique spreading code assigned differently, and transmitted power control is performed. A base station apparatus in a code division multiple access mobile communication system that constantly transmits a fixed perch channel having a constant transmission power, and receives each perch channel of a peripheral cell during communication with the mobile station. A first receiving means for causing the mobile station to measure the level, transmitting the measurement result, and receiving the transmitted measurement result; and a first predetermined level among the reception levels received by the first receiving means. First detecting means for detecting a cell having a reception level that is smaller than a first predetermined level difference between a reception level exceeding the reception level of the first communication level and a maximum reception level during communication; A second receiving means for causing the mobile station to measure the reception levels of the number of cells, transmitting the measurement result, and receiving the transmitted measurement result; Cell in which the level difference between the reception level of each of the cells and the maximum reception level among the reception levels is larger than a second predetermined level difference that is larger than the first predetermined level difference, or simultaneous communication. And a second detection unit for detecting a cell whose medium reception level is lower than a second predetermined reception level which is lower than the first predetermined reception level.

In the base station apparatus according to the present invention, the first receiving means notifies the mobile station of a spreading code of a neighboring cell, and the mobile station uses the notified spreading code to transmit each of the neighboring cells. And a measuring means for measuring the reception level of the perch channel.

Furthermore, the gist of the present invention is that the base station apparatus of the present invention further comprises simultaneous communication means for newly connecting the cell detected by the first detection means to the mobile station and entering the simultaneous communication mode. .

The base station apparatus according to the present invention further includes a notifying means for notifying the mobile station of the cell detected by the first detecting means, and the mobile station receiving the notification newly connects the cell. The point is to control to enter the simultaneous communication mode with the cell.

Further, the gist of the present invention is that the base station apparatus of the present invention further comprises a disconnecting means for disconnecting the line for the cell detected by the second detecting means.

The base station apparatus according to the present invention further includes a notifying means for notifying the mobile station of the cell detected by the second detecting means, and the mobile station having received the notification disconnects the line for the cell. That is the gist.

[0023]

According to the mobile communication handover method of the present invention, the mobile station determines the level of the reception level exceeding the first predetermined reception level and the maximum reception level among the reception levels of the perch channels of the neighboring cells measured during communication. A cell whose reception level is smaller than the first predetermined level difference is newly connected to enter the simultaneous communication mode, and the level difference between the reception level of the plurality of cells performing simultaneous communication and the maximum reception level is the first predetermined level. If the second predetermined level difference is larger than the second predetermined level difference, or if the reception level during simultaneous communication is smaller than a second predetermined reception level smaller than the first predetermined reception level, The line for the cell is disconnected.

In addition, in the mobile communication handover method of the present invention, in addition to the above, a spreading code of a neighboring cell is notified from a communicating base station, and the received level of a perch channel of the neighboring cell is notified using the spreading code. Measure.

Further, in the mobile station apparatus according to the present invention, among the reception levels of the perch channels of the neighboring cells measured during communication, the level difference between the reception level exceeding the first predetermined reception level and the maximum reception level is obtained. A cell having a reception level smaller than the first predetermined level difference is detected, and the level difference between the reception level of the plurality of cells during simultaneous communication and the maximum reception level is equal to the first reception level.
Cell that has become larger than the second predetermined level difference that is larger than the predetermined level difference, or the reception level during simultaneous communication becomes smaller than the second predetermined reception level that is smaller than the first predetermined reception level. Detected cell.

In the mobile station apparatus of the present invention,
The spreading code of the neighboring cell is notified from the base station in communication, and the received level of the perch channel of the neighboring cell is measured using the spreading code.

In the mobile station apparatus according to the present invention, the first
The cell newly detected by the detecting means is newly connected to enter the simultaneous communication mode with the cell.

Further, in the mobile station apparatus of the present invention, the first station
Notify the cell detected by the detecting means of the base station,
The base station that has received the notification controls the cell so as to newly connect the cell to the mobile station and enter the simultaneous communication mode with the cell.

Further, in the mobile station apparatus according to the present invention, the line for the cell detected by the second detecting means is disconnected.

Further, in the mobile station apparatus of the present invention, the second station
The cell detected by the detecting means is notified to the base station, and the base station that has received the notification performs control to disconnect the line for the cell.

In the base station apparatus according to the present invention, the mobile station measures the reception level of the perch channel of the neighboring cell during communication with the mobile station, and exceeds the first predetermined reception level among the reception levels. A cell having a reception level whose difference between the reception level and the maximum reception level is smaller than a first predetermined level difference is detected, and the mobile station measures the reception levels of a plurality of cells performing simultaneous communication, and The cell whose level difference from the maximum reception level is larger than the first predetermined level difference is larger than the second predetermined level difference, or the cell whose reception level during simultaneous communication is smaller than the first predetermined reception level. The cell which has become smaller than the second predetermined reception level is detected.

Further, in the base station apparatus of the present invention, in the above, the spreading code of the neighboring cell is notified to the mobile station, and the mobile station measures the reception level of the perch channel of the neighboring cell using the spreading code.

Further, in the base station apparatus of the present invention, the first station
The cell detected by the detecting means is newly connected to the mobile station to enter the simultaneous communication mode.

In the base station apparatus according to the present invention, the cell detected by the first detecting means is notified to the mobile station, and the mobile station receiving the notification newly connects the cell and performs simultaneous communication with the cell. Control to enter the mode.

Further, in the base station apparatus of the present invention, the second station
The line for the cell detected by the detecting means is disconnected.

In the base station apparatus of the present invention, the cell detected by the second detecting means is notified to the mobile station, and the mobile station receiving the notification disconnects the line for the cell.

[0037]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart showing a processing procedure of a mobile communication handover method according to one embodiment of the present invention. The mobile communication handover method shown in FIG. 1 performs a handover process required when a mobile station moves from a cell currently in communication to another cell in a CDMA mobile communication system using spread spectrum codes. In this handover process, in order to select the next cell to communicate with by moving the mobile station, the perch channel that the base station of each cell is constantly transmitting, that is, modulated at the same frequency, Spread with the assigned unique spreading code, measure the reception level of the transmission power constant perch channel that does not perform transmission power control, select a cell for handover based on this reception level and the level difference described below, After entering the simultaneous communication mode with this cell, further disconnect the communication with the cell under communication under predetermined conditions, It is adapted to perform Ndooba.

FIG. 2 is a block diagram showing a configuration of the mobile station transmitting / receiving section 10 and the base station 20 for implementing the mobile communication handover method of FIG. The mobile station transmitting / receiving unit 10 includes an antenna 11 for communicating with the base station 20,
1 has a transmission circuit unit 13 and a reception circuit unit 14 connected via a transmission / reception switch 12, and a control unit 15 connected to the transmission circuit unit 13 and the reception circuit unit 14. The receiving circuit unit 14 receives the perch channel transmitted from the base station 20 via the antenna 11 and the transmission / reception switch 12, measures the reception level of the received perch channel, and measures the measured reception level. Control level 15
To be supplied. Further, the control unit 15 compares the reception levels of the perch channels of the cells supplied from the reception circuit unit 14 with each other as described in the processing of FIG. A level difference from the reception level is calculated, a cell to be simultaneously connected and a cell to be disconnected are determined based on the reception level and the level difference, and a handover is performed.

In the base station 20 shown in FIG.
The base station amplifier 26 to which the antenna 21 for communicating with the mobile station transmitting / receiving unit 10 is connected is connected to a modulation / demodulation device 27, which is connected to a spreading device 28. The modulation / demodulation device 27 has a control bus control 3
0, a supervisory control device 31, a 2M / 1.5M interface device 32, a base station control device 33, and a timing supply device 34.

The transmission data for the perch channel generated in the base station 20 configured as described above is spread by the spreading code for level monitoring in the spreading device 28, and further added to the carrier signal by the modulation and demodulation device 27. The modulation output signal of the modem 27 is transmitted to the base station amplifier 26.
And transmitted as a radio wave from the antenna 21. In FIG. 2, the base station 20 shows only the circuit configuration of the transmission system and does not show the circuit configuration of the reception system. However, since the circuit configuration of the reception system is an ordinary well-known one, it is not shown. .

Next, the processing procedure of the mobile communication handover method will be described with reference to the flowchart shown in FIG.

In FIG. 1, a mobile station is notified of a spreading code of a neighboring cell from a base station during communication, sequentially receives a perch channel of a neighboring cell using the spreading code, and measures a reception level R thereof ( Step 110). Specifically, the spreading code of the perch channel from the base station is despread with the spreading code, and the reception level R is measured.

Then, of the measured reception levels R, the reception level R exceeding the first predetermined reception level R1
And a maximum reception level during communication is calculated (step 120). The calculated level difference D ′ is the first
, A cell having a reception level smaller than the predetermined level difference D1 is newly connected and the simultaneous communication mode is entered (step 13).
0).

The above relationship will be described with reference to FIG. FIGS. 3A, 3B, and 3C are explanatory diagrams showing a positional relationship, a reception level, and a level difference between the cell and the mobile station when the mobile station MS moves from the cell A to the cell B, respectively. It is. As shown in FIG. 3A, a mobile station MS existing in one cell A of two adjacent cells A and B having base stations BSa and BSb, respectively, is indicated by a dotted line as indicated by an arrow 91. When moving from cell A to cell B to the right along 93, the reception level R of the perch channel received from the base stations BSa and BSb as the mobile station MS moves is shown in FIG. To change. That is, FIG. 3B shows the reception level R on the vertical axis, and the position P of the mobile station MS along the dotted line 93 on the horizontal axis. In FIG. 3B, Ra indicates that the mobile station MS is the base station BSa. , The reception level of the perch channel received from the base station BS. The reception level Ra becomes maximum when the mobile station MS comes closest to the base station BSa, and becomes smaller as the mobile station MS moves away from the base station BSa. Rb indicates that the mobile station MS is the base station BSb
Similarly, the reception level of the perch channel received from.

First, when the mobile station MS existing in the cell A and communicating with the base station BSa moves along the dotted line 93 as shown by an arrow 91, the mobile station MS is notified from the base station BSa. It is constantly searching to receive a perch channel constantly transmitted from the base station BSb of the cell B which is a neighboring cell. When the mobile station MS is near the center of the cell A, the mobile station MS cannot yet receive the perch channel from the base station BSb, but the mobile station MS is located near the periphery away from the center of the cell A. At P10, as indicated by Rb in FIG.
The perch channel from b can be received. However, the reception level Rb at this position P10 is
In (b), the reception level is equal to or lower than the first predetermined reception level R1 indicated by a dotted line. When the mobile station MS further moves closer to the cell B and reaches the position P11, the reception level Rb of the cell B from the base station BSb becomes equal to or higher than the first predetermined reception level R1.

The mobile station MS has a first predetermined reception level R
When one or more reception levels Rb are detected, a level difference D 'between the reception level Rb and the reception level currently being communicated, that is, the reception level Ra from the base station BSa of the cell A in FIG. Is calculated by Ra-Rb. If the level difference D 'is smaller than the first level difference D1 as shown in FIG.
S newly connects the base station BSb of the cell B having the small level difference, and enters the simultaneous communication mode with the base station BSb.

Returning to FIG. 1, the mobile station that has entered the simultaneous communication mode as described above always measures the reception levels R of a plurality of cells during simultaneous communication, and determines each of these reception levels R and the reception level. A level difference D "from the maximum reception level among the levels R is calculated, and this level difference D" is larger than the first predetermined level difference D1. The second predetermined level shown in FIG. It is determined whether the difference is larger than the difference D2 (step 140). As a result, when the level difference D "becomes larger than the second predetermined level difference D2, the communication line for the cell having this level difference D" is disconnected (step 160), and the cell having the maximum reception level is disconnected. Continue communication with.

More specifically, referring to FIG. 3, when the base station BSb of the cell B is newly connected at the position P11 in FIG. 3, the mobile station MS is connected to the base station BSa of the cell A and the cell B in the simultaneous communication mode with the base station BSb, and receiving levels Ra from the cells A and B.
And Rb are constantly monitored. When the mobile station MS moves further in this state, the reception level Ra from the cell A becomes as shown in FIG.
As shown in (b), the cell B gradually decreases.
, The reception level Rb gradually increases, and the level difference D ″ between the two reception levels also increases gradually. As a result, the mobile station MS.
Moves to the position P12, the level difference D ″
As shown in (c), when the difference becomes larger than the second predetermined level difference D2, the cell having the level difference D ", that is, the communication line for the cell A is disconnected, and the cell B which is the cell having the maximum reception level remains. Will be.

Returning to FIG. 1, as a result of the determination at step 140, the level difference D ″ is equal to the second predetermined level difference D2.
If not, go to step 150,
The second predetermined reception level R2 in which the reception level R of the cell performing simultaneous communication is smaller than the first predetermined reception level R1
It is determined whether it is smaller than. If the reception level R is not lower than the second predetermined reception level R2, the process returns to step 140, and the same processing is repeated. If the reception level R is lower, the line for the cell is disconnected (step 16).
0). It should be noted that the determination using the second reception level R2 is mainly performed for a signal having a low reception level.

Next, with reference to a flowchart shown in FIG. 4, a processing procedure of a base station which executes a mobile communication handover method according to another embodiment of the present invention will be described.

In FIG. 4, the base station notifies the mobile station in communication of the spreading code of the neighboring cell, and causes the mobile station to sequentially receive the perch channels of the neighboring cell using the spreading code. R is measured (step 21)
0). Then, the reception level R measured by the mobile station is transmitted and received by the base station (step 220). The base station calculates a level difference D 'between the reception level R larger than the first predetermined reception level R1 and the maximum reception level during communication (Step 230), among the received reception levels R (Step 230). Connects a cell having a reception level R smaller than the first predetermined level difference D1 to the mobile station, and enters the simultaneous communication mode (step 240).

The base station causes the mobile station to measure the reception level of the cell under simultaneous communication, transmits the measurement result to the mobile station, and receives it at the base station (step 250). The base station calculates a level difference D "between each of the received reception levels R and the maximum reception level among the reception levels R, and the level difference D" is larger than the second predetermined level difference D2. It is determined whether or not this is the case (step 260). As a result, if the level difference D "is larger than the second predetermined level difference D2, the communication line for the cell having this level difference D" is disconnected (step 290).

If it is determined in step 260 that the level difference D ″ is not larger than the second predetermined level difference D2, the process proceeds to step 270, and the mobile station measures the reception level R of the cell performing simultaneous communication. Then, it is determined whether or not the reception level R is lower than a second predetermined reception level R2 which is lower than the first predetermined reception level R1 (step 280). If it is not lower than the predetermined reception level R2, step 2
Returning to step 50, the same processing is repeated, but if it is smaller, the line for the cell is disconnected (step 29).
0).

[0055]

As described above, according to the present invention,
A cell having a reception level of a perch channel of a neighboring cell during communication exceeding a first predetermined reception level and a level difference between the maximum reception level and the reception level of the perch channel exceeding the first predetermined level is newly connected. Detecting a cell in which the level difference between the reception level and the maximum reception level of a plurality of cells during simultaneous communication is larger than a second predetermined level difference that is larger than the first predetermined level difference, and a line for the cell is detected. Since disconnection eliminates the need to select and connect a cell requiring a large communication channel transmission power at a location close to the base station for handover, it is difficult for the large transmission power to interfere with communication in other cells. , Subscriber capacity can be increased, and those with smaller reception level differences are connected and those with larger reception levels are disconnected,
The flutter of handover can be suppressed.

According to the present invention, under the control of the base station apparatus, the mobile station causes the mobile station to measure the reception level of the perch channel of the neighboring cell, and the reception level exceeding the first predetermined reception level is obtained. The level difference between the level and the maximum reception level is the first
A cell having a reception level smaller than the predetermined level difference is detected, the cell is connected to the mobile station, and the mobile station measures the reception levels of a plurality of cells during simultaneous communication. A cell whose level difference is larger than a second predetermined level difference is larger than a second predetermined level difference, and a line for the cell is disconnected, so that a large communication channel transmission power near a base station is used. Since it is no longer necessary to select and connect a cell that requires a signal for handover, it is difficult to interfere with communication of other cells with a large transmission power, and it is possible to increase the subscriber capacity and to increase the reception level. Since the connection with the smaller difference is connected and the connection with the larger difference is disconnected, the flutter of handover can be suppressed, and the handover is further controlled by the base station. Because doing over control in the mobile station, determining, processing the base station of memory and the like can be performed commonly, it is possible to simplify the configuration and processing of the mobile station.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing procedure of a mobile communication handover method according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a mobile station and a base station that implement the mobile communication handover method of FIG.

FIG. 3 is an explanatory diagram showing a positional relationship between a cell and a mobile station, a reception level, and a level difference when the mobile station moves from a cell A to a cell B.

FIG. 4 is a flowchart showing a processing procedure of a base station implementing a mobile communication handover method according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a relationship between a plurality of cells constituting a service area of a CDMA mobile communication system and a mobile station moving in the plurality of cells.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 mobile station transmission / reception unit 12 transmission / reception switch 13 transmission circuit unit 14 reception circuit unit 15 control unit 20 base station 21 antenna 26 base station amplifier 27 modulation / demodulation device 28 spreading device 30 control bus control 31 supervisory control device 32 2M / 1.5M interface Device 33 Base station controller 34 Timing supply device

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 7/26-7/26 113 H04Q 7/04-7/38 H04J 13/00-13/06

Claims (14)

(57) [Claims] 1. A base station is provided in each of a plurality of cells,
Each base station is modulated with the same frequency, spread with a unique spreading code assigned differently, and constantly transmits a perch channel with a constant transmission power without performing transmission power control. A mobile communication handover method in a communication system, wherein a mobile station measures a reception level of each perch channel of a peripheral cell during communication, and determines a reception level exceeding a first predetermined reception level among the reception levels. A cell having a reception level smaller than the first predetermined level difference from the maximum reception level during communication is newly connected to the mobile station to enter the simultaneous communication mode, and a plurality of cells performing simultaneous communication in the mobile station Is a second predetermined level in which a level difference between each of the reception levels and the maximum reception level among the reception levels is larger than the first predetermined level difference. The line for the cell is cut off when the reception level becomes higher or when the reception level during simultaneous communication becomes lower than a second predetermined reception level lower than the first predetermined reception level. Mobile communication handover method. 2. The step of measuring the reception level,
2. The mobile station according to claim 1, wherein a spreading code of a neighboring cell is notified from a base station that is currently communicating, and a reception level of each perch channel of the surrounding cell is measured using the notified spreading code. Communication handover method. 3. A base station is provided in each of the plurality of cells,
Each base station is modulated with the same frequency, spread with a unique spreading code assigned differently, and constantly transmits a perch channel with a constant transmission power without performing transmission power control. A mobile station device in a communication system, comprising: measuring means for measuring a reception level of each perch channel of a peripheral cell during communication; and a first predetermined reception level among the reception levels measured by the measurement means. First detection means for detecting a cell having a reception level having a level difference between the exceeding reception level and the maximum reception level during communication smaller than a first predetermined level difference; and detecting a reception level of a plurality of cells during simultaneous communication. The level difference between each of them and the maximum reception level among the reception levels is the first difference.
Or a cell whose reception level during simultaneous communication is larger than a second predetermined reception level which is larger than a second predetermined reception level which is smaller than the first predetermined reception level. A second detecting means for detecting a lost cell. 4. The measuring means is notified of a spreading code of a neighboring cell from a base station currently in communication, and measures the reception level of each perch channel of the neighboring cell using the notified spreading code. The mobile station device according to claim 3, comprising: 5. The mobile station apparatus according to claim 3, further comprising a simultaneous communication unit for newly connecting a cell detected by said first detection unit and entering a simultaneous communication mode with the cell. 6. A notifying unit for notifying a cell detected by the first detecting unit to a base station, and the base station receiving the notification newly connects the cell to a mobile station, and connects the cell to the mobile station. 4. The mobile station apparatus according to claim 3, wherein the mobile station apparatus is controlled to enter a simultaneous communication mode. 7. The mobile station apparatus according to claim 3, further comprising a disconnection unit that disconnects a line for the cell detected by said second detection unit. 8. A communication apparatus for notifying a cell detected by the second detection means to a base station, wherein the base station receiving the notification performs control to disconnect a line for the cell. The mobile station device according to claim 3, wherein 9. A base station is provided in each of the plurality of cells,
Each base station is modulated with the same frequency, spread with a unique spreading code assigned differently, and constantly transmits a perch channel with a constant transmission power without performing transmission power control. A base station device in a communication system, comprising: causing a mobile station to measure a reception level of each perch channel of a peripheral cell during communication with the mobile station; transmitting the measurement result; and transmitting the transmitted measurement result. A first receiving means for receiving, a level difference between a reception level exceeding a first predetermined reception level and a maximum reception level during communication among the reception levels received by the first reception means is a first predetermined level; First detecting means for detecting a cell having a reception level smaller than the level difference between the mobile station and the mobile station, the mobile station measures the reception levels of a plurality of cells performing simultaneous communication, and transmits the measurement result; Second receiving means for receiving the measurement result transmitted by the second receiving means, and the level of the reception level of each of the plurality of cells in simultaneous communication received by the second reception means and the maximum reception level among the reception levels A cell whose difference is larger than a second predetermined level difference that is larger than the first predetermined level difference, or a second predetermined level whose reception level during simultaneous communication is smaller than the first predetermined level. A base station apparatus comprising: a second detection unit configured to detect a cell whose reception level is lower than the reception level. 10. The first receiving means notifies a spreading code of a neighboring cell to a mobile station, and the mobile station measures a reception level of each perch channel of the surrounding cell using the notified spreading code. The base station apparatus according to claim 9, further comprising a measuring unit that performs measurement. 11. The base station apparatus according to claim 9, further comprising simultaneous communication means for newly connecting a cell detected by said first detection means to a mobile station to enter a simultaneous communication mode. . 12. The mobile station further includes a notifying unit for notifying a mobile station of a cell detected by the first detecting unit, and the mobile station receiving the notification newly connects the cell and performs simultaneous communication with the cell. 10. A control to enter a mode.
The base station device as described in the above. 13. The base station apparatus according to claim 9, further comprising a disconnecting means for disconnecting a line for the cell detected by said second detecting means. 14. The mobile station further comprising: a notifying unit for notifying a mobile station of a cell detected by the second detecting unit, and the mobile station receiving the notification disconnects a line for the cell. Item 10. The base station device according to item 9.