JP2972476B2 - Base station selection method and base station selection method for cellular wireless telephone system - Google Patents

Abstract

PURPOSE:To improve the utilizing efficiency of entire radio channels of the system by installing an auxiliary base station having only a common control radio channel to a zone where service areas by general base stations are overlapped and controlling the auxiliary base station with a control station. CONSTITUTION:General base stations 5-8 each has a common control radio channel and a speech radio channel and have service areas 15-19. An auxiliary base station 4 is installed to areas overlapped by service areas 15-18 and has only a common control radio channel and has a service area 14. Then each of base stations 4-9 is controlled by a control station 1 via communication lines 34-39. For example, when a mobile station 3 on a road 10 makes a call to the auxiliary base station 4 on the service area 14, the auxiliary base station 4 gives a command of deciding a re-calling destination to be a base station 8 having a room for its channel to the mobile station 3. That is, the call transfer destination is prepared in the control station 1 and the traffic of the overlapped service area with an adjacent cell is introduced to one cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base station selection method and a base station selection method for a cellular radio telephone system.

[0002]

2. Description of the Related Art In a conventional cellular radio telephone system, a mobile station selects a radio base station having the best radio wave reception state. Switching is performed to the base station that is determined to have the best reception state.

[0003]

The installation point of the base station and its service area in the cellular radio telephone system are determined by preferentially selecting the most desirable place from the expected distribution of the mobile station traffic and the radio wave propagation arrangement. Alternatively, the service area configuration is not always as planned due to the geographical location of the actual base station and the structural conditions of the building. In addition, the traffic distribution of the mobile station greatly varies depending on the time of day.

Here, in the conventional cellular radio telephone system, when one cell of adjacent cells is congested and another cell has an area where there is room in the other cell, a part of the traffic of the mobile station is spared. There is a problem that it is not possible to rescue a congested cell by guiding to a certain cell.

On the other hand, from the viewpoint of processing load in the cellular radio telephone system, the processing amount used for channel switching tends to be the second largest after the processing amount for setting a communication path for a new call. Further, in an actual field, it is well known that the point at which channel switching occurs is almost fixed, and moreover, a short section has a large number of unique sections in which channel switching is repeated twice or three times. .

Most of the singular sections are not the best cells at that time, but the number of times of channel switching can be reduced by assigning sufficiently good radio channels to the second and third cells. The wireless telephone system has a problem that this cannot be performed.

[0007] It is an object of the present invention to provide a cellular radiotelephone network composed of general base stations in a plurality of base stations overlapping one another, in which a specific area or channel switching with large temporal traffic fluctuation is continuously performed. By installing an auxiliary base station that has only a common control radio channel and no communication radio channel at a unique point where the problem occurs, the control station controls both the general base station and the auxiliary base station, thereby causing the above problem. It is an object of the present invention to provide a base station selection method for a cellular radio telephone system which solves the above problems.

[0008]

According to the first aspect of the present invention , in a cellular radio telephone system, only a common control radio channel is provided in an area where service areas of a plurality of general base stations are overlapped, and a communication radio channel is provided. When an auxiliary base station having no auxiliary base station is installed, and the mobile station that has set the common control radio channel of the auxiliary base station as a standby channel responds to a calling or incoming call, the auxiliary base station is given in advance by the control station. Instruction means for instructing the auxiliary base station to re-transmit to one of the general base stations having overlapping service areas, and re-prioritizing the auxiliary base station to a channel switching destination while the mobile station is moving. Selection means for preferentially selecting the general base station predetermined in the control station when a switching request is issued to the control station as a candidate Cellular type, characterized in that it comprises a
A base station selection scheme for a wireless telephone system is obtained .

According to the second aspect of the present invention , in order to cope with the necessity for the mobile station to perform channel switching during communication, a candidate base station for switching is scanned and measured in advance, and a plurality of candidate base stations for switching are determined. a base station selection how a cellular radiotelephone system data stations the mobile station transmits during a channel switch request to the system, without a call for a radio channel, the base of the system common control radio channel It has only a station-to-mobile station transmission function, does not have a standby channel, has a built-in basic format of data to be transmitted in advance, and communicates with the control station whenever it is necessary to change system parameters and monitor the base station. in connecting, placed not accept the actual outgoing calls and incoming call response call supplementary base station to the area of overlap the service areas according to a plurality of other general base station, When the mobile station has requested the control station to switch to the auxiliary base station as the top priority candidate of the channel switching destination while moving, the general station predetermined from the positional relationship with the base station in communication with the control station in the control station. Cellular wireless system characterized by preferentially selecting a base station
A method for selecting a base station of a talk system is obtained .

[0010]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a cellular radiotelephone system showing a first embodiment of the first invention. FIG. 2 is a block diagram of a control station in FIG. 1 for controlling transmission and controlling a channel switching priority base station. FIG. 6 is a diagram illustrating an example of a management table in operation.

The cellular wireless telephone system of the present embodiment is
As shown in FIG. 1, the base station includes general base stations 5, 6, 7, and 8, an auxiliary base station 4, and a control station 1. The general base stations 5, 6, 7, and 8 each have a common control radio channel and a communication radio channel, and
It has 16, 17, 18, and 19. The auxiliary base station 4 is installed in an area where the service areas 15, 17, and 18 are overlapped, has no communication radio channel, has only a common control radio channel, and has a service area 14. Each of the base stations 4, 5, 6, 7, 8, 9 communicates with the control station 1 via a communication line 34, 35, 36, 37, 38, 39, respectively.
Is controlled by The control station 1 is connected to the maintenance terminal 2 and another communication network 11.

In the auxiliary base station 4, as shown in FIG.
In the time period from 10:00 to 16:00, the general base station 8 is used as the transmission conversion destination base station (transmission control 1), and in the time period from 16:00 to 14:00 on the next day, the general base station 7 is used as the transmission conversion destination base station. (Transmission control 2). This management table can be changed by a maintenance person from the maintenance terminal 2 (shown in FIG. 1) of the control station 1.

Here, it is assumed that the service area 14 is stronger than the radio wave of the base station 7 as a condition for explanation. In the service area 17, the traffic becomes very high from 14:00 to 16:00, and the whole channel of the base station 7 is busy at a considerable frequency. It is assumed that there is.

Now, when the mobile station 3 traveling on the road 10 makes a call to the auxiliary base station 4 in the service area 14,
The auxiliary base station 4 gives an instruction to re-transmit to one of the service areas 15, 17, or 18 in this area based on information previously given from the control station 1 via the communication line 34.

For example, when the auxiliary base station 4 receives a call before 14:00 according to the instruction of the control station 1, it gives the mobile station 3 an instruction to set the retransmission destination to the base station 8.

The call transfer destination and the schedule are prepared in the control station 1 as a management table shown in FIG. 2, and the control station 1 determines the start time (FROM HHMM) in the management table when the base station operation data of the system is updated. The data is transferred to the auxiliary base station 4 when the maintenance data is changed by the maintenance person.

As described above, in this embodiment, the traffic of the overlapping service area with the adjacent cell is guided to one of the cells, so that the service area of the base station is substantially partially changed.

Next, the wireless channel switching operation in the present embodiment will be described.

First, a state before the auxiliary base station 4 is installed, that is, a conventional system will be described. The mobile station 3 travels on the road 10 from the bottom of FIG.
0 starts communication via the base station 5.

The mobile station 3 issues a radio channel switching request when it goes out of the service area 15 of the base station 5 at the point 21. The control station 1 determines that the base station 7 is the best cell based on the report from the mobile station 3 and executes the wireless channel switching.

Next, the mobile station 3 requests channel switching again because the mobile station 3 goes out of the service area 17 at the point 22, and the control station 1 selects the base station 8 as the best cell based on the report of the mobile station 3. Perform channel switching.

Thereafter, it is assumed that the mobile station 3 issues a channel switching request again at the point 23, switches the channel to the base station 9 by the control station 1, and terminates the communication at the point 24.

Here, paying attention to the point 21, the base station 7
Is better than that of base station 8, base station 7 was selected as the channel switching destination. However, since the service area 17 retreats at the point 22 due to the influence of the terrain and the structure, the mobile station 3 needs to switch the channel again after moving in an extremely short section.

On the other hand, since the point 21 is also within the service area of the base station 8, if the channel is switched from the base station 5 to the wireless channel of the base station 8 at the point 21, the channel switching at the point 22 becomes unnecessary. .

That is, in this example, the mobile station 3 is located at the point 2
Although three channel switching services of 1, 22, and 23 are received, it is possible to reduce the number of channel switching of points 21 and 23 to two.

Although it is desirable that a point such as the point 21 does not occur as much as possible on an arterial road where there is a lot of traffic, it often becomes apparent from actual measurements and tests after the station is installed.

Next, the radio channel switching operation in this embodiment after the installation of the auxiliary base station will be described with reference to FIG.

FIG. 3 is a flowchart showing a part of a channel switching request processing flow performed by the control station in FIG.

In this embodiment, as described above, the auxiliary base station 4 dedicated to the common control radio channel is installed at the point 21 in the area where the service areas 15, 17, and 18 overlap. The output of the auxiliary base station 4 has a service area 14 limited to the vicinity of the overlapping area.

The elevation up the supplementary base station 4 the mobile station 3 as the highest priority candidate destination switch channel in the vicinity of the point 21, when the switching channel to the base station 5 in the communication request (step 10
1), the base station 5 transmits a channel switching request to the control station 1 via the communication line 35.

The control station 1 determines whether the auxiliary base station 4 listed by the mobile station 3 has the first priority as a switching candidate (step 102), and if YES here, the auxiliary base station in the management table shown in FIG. Referring to the station operation data (step 103), in the channel switching, the base station 5 is selected prior to the switching , and the base station 8 is preferentially selected when the switching destination is the auxiliary base station 4.

That is, referring to the management table in FIG. 3, it is determined whether or not the existing cell is equal to the improvement countermeasure cell (step 104). If it is equal (YES in step 104), the cell to be switched is extracted from the management table (step 104). Step 105).
Then, it is checked whether there is an empty channel (step 10).
6) If there is an empty channel (YE in step 106 )
S) Execute channel switching (step 107).

Further, NO in step 102, that is, when the candidate <br/> first priority is not supplementary base station, N in step 104
If O, that is, if the existing cell is not an improvement countermeasure cell, and if NO in step 106 , that is, if there is no vacant channel, the reception level priority selection channel excluding the auxiliary base station is switched (step 108).

In this case, in preparation for the need for the mobile station 3 to perform channel switching during communication, the switching destination candidate base station is scanned and measured in advance, and data of a plurality of switching destination candidate base stations is transmitted from the mobile station 3 to the mobile station 3. Although the case where transmission is performed when there is a channel switching request to the system has been described in detail, in the case of channel switching, when the control station 1 instructs a plurality of base stations to perform base station selection of a switching destination channel, measurement is also performed. Similarly, the priority of the switching destination base station is changed.

Next, a second embodiment of the first invention will be described with reference to FIGS. This embodiment is a further development of the first embodiment of the first invention.

FIG. 4 is a diagram showing an example of a management table built in by a control station for managing transmission control and channel switching priority base stations in the second embodiment of the first invention.
5 is a flowchart showing a processing flow for updating a management table shown in FIG. 4 based on periodic traffic data performed by the control station in FIG. 1.

The information given from the control station 1 to the auxiliary base station 4 is the same as in the first embodiment, but the control station 1 creates and updates the management table shown in FIG.

That is, the auxiliary base station 4 measures the actual traffic state of each base station for the destination of the traffic of the outgoing or incoming call response received as the first priority, and performs periodic traffic data aggregation (step 201). Select an affordable base station.

The control station 1 creates the latest usage rate for each auxiliary base station from the results of the periodic traffic observation (step 202), compares the contents with the previous update as needed (step 203), and communicates the result. Instruct the auxiliary base station 4 via the line 34.

Then, it is checked whether or not the transfer destination data has been updated for each auxiliary base station (step 204). Since the auxiliary base station 4 has data update, the update data is transmitted (step 205). In step 4, the current usage rate data in the management table shown in FIG. 4 is updated (step 206).

Next, the second invention will be described with reference to FIGS. 1, 6, and 7. FIG. FIG. 6 is a system block diagram showing the first embodiment of the second invention. The operation of the control station 1 in response to a channel switching request from a communicating mobile station is exactly the same as that of the first embodiment of the first invention. It is.

In FIG. 1, between the control station 1 and each base station, a unique signal associated with each communication of a communication channel and signal data of a common control radio channel are generally connected by a common data line. In this data line, as a protocol, X.T. 25 or No. 7 common line signals or their equivalents are used.

However, in the cellular radio telephone system according to the present embodiment, the auxiliary base station 4 shown in FIG. 6 is not notified to the mobile station 3 as a standby channel target station. Is not accepted, and no incoming call (generally called a page) is performed. Therefore, the contents processed by the auxiliary base station 4 are also fixed, and there is no need to communicate with the control station 1 for each actual call.

[0045] In this embodiment, between the supplementary base station 4 control station 1 as shown in FIG. 6, connects whenever necessary via the public telephone network 6 2 via public subscriber line 61, respectively.
This communication line changes the content of the broadcast data of the common control wireless channel of the system, that is, for example, changes the output of the auxiliary base station 4 temporally to change the size of the area where the channel switching destination is guided. It is used for operation monitoring such as the time and the alarm output of the auxiliary base station 4.

Next, a second embodiment of the second invention will be described with reference to FIG. FIG. 7 is a system block diagram showing a second embodiment of the second invention.

In FIG. 7, the function of the auxiliary base station 4 as viewed from the mobile station 3 is exactly the same as that of the first embodiment of the second invention shown in FIG. The information transmission means that connects

In this embodiment, a wireless telephone communication line provided to the mobile station 3 by the system is used as necessary as information transmission means for connecting the control station 1 and the auxiliary base station 4. The communication procedure also uses the system standard procedure. The transceiver 71 is installed together with the auxiliary base station 4 and uses, for example, standard connection means and communication procedures for the mobile station data terminal service with the auxiliary base station 4.

The control station 1 transmits broadcast information transmitted from the auxiliary base station 4 and control information associated with operation monitoring in the form of a data communication call via the nearest general base station 7. Also,
The alarm of the base station 4 or the transceiver 71 is transmitted to the transceiver 71.
To the control station 1 via a general base station 7 in a system standard data communication procedure.

[0050]

As described above, according to the present invention, in a system having a base station in which congestion occurs due to a time zone and an adjacent base station which is not congested in the time zone, the traffic of the congested base station is reduced. In part, by performing traffic guidance to a base station that is not congested in an area where service areas overlap, this has the effect of significantly improving the wireless channel usage efficiency of the entire system. This is particularly effective when performing dynamic channel assignment (DCA), which varies depending on the time of day or changes the size of the service area depending on the time of day, within a fixed overlapped service area. Have.

Furthermore, since the number of times of channel switching can be reduced in the cellular radio telephone system, the processing amount of the central processing unit is reduced, and as a result, the subscriber capacity of the system is improved.

Further, in the second invention, the communication line between the control station and the auxiliary base station is connected not only to a high-speed and large-capacity dedicated line but also to a low-speed voice line or a general communication line of a cellular radio telephone system whenever necessary. Therefore, there is an effect that the cost of the communication line is reduced and each line device connecting the control station and the auxiliary base station is simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram of a cellular radio telephone system showing a first embodiment of the first invention.

FIG. 2 is a diagram showing an example of a management table built in by a control station in FIG. 1 to manage transmission control and channel switching priority base stations.

FIG. 3 is a flowchart showing a part of a channel switching request processing flow performed by a control station in FIG. 1;

FIG. 4 is a diagram showing an example of a management table incorporated in a control station in the second embodiment of the first invention for managing transmission control and channel switching priority base stations.

5 is a flowchart showing a processing flow for updating a management table shown in FIG. 4 based on periodic traffic data performed by a control station in FIG. 1.

FIG. 6 is a system block diagram showing a first embodiment of the second invention.

FIG. 7 is a system block diagram showing a second embodiment of the second invention.

[Explanation of symbols]

1 control station 2 maintenance terminal 3 mobile station 4 supplementary base station 5, ..., 9 ordinary base station 10 road 11 other communications networks 14, ..., 19 service areas 20, ..., 24 point 3 4, ..., 39 communication line 61 Public subscriber line 62 Public telephone communication network 74 Transceiver

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H04B 7/24-7/26 H04Q 7/00-7/38

Claims (2)

(57) [Claims] An auxiliary base station having only a common control radio channel and no communication radio channel is installed in an area where service areas of a plurality of general base stations overlap in a cellular radio telephone system. When the mobile station that has set the common control radio channel of the base station as the standby channel responds to the calling or incoming call, the auxiliary base station has the service area overlapping with the auxiliary base station given in advance by the control station. Instruction means for instructing one of the general base stations to transmit again, and when the mobile station requests the control station to switch to the auxiliary base station as the highest priority candidate for channel switching while the mobile station is moving, Selecting means for preferentially selecting the general base station predetermined in the control station. Base station selection method for line telephone system. 2. The mobile station scans and measures a switching destination candidate base station in advance in order to cope with the need for channel switching during communication, and the mobile station transmits data of a plurality of switching destination candidate base stations. a base station selection <br/> how cellular radiotelephone system for transmitting during the channel switch request to the system, without a call for a radio channel, the base station for mobile stations in the system common control radio channel It has only a transmission function, and does not have a standby channel, has a built-in basic format of data to be transmitted in advance, connects a control station with a control station whenever a change in system parameters and base station monitoring are required, It established the actual outgoing calls and incoming calls answered calls and a not accepted supplementary base station in the area overlapping service area by a plurality of other general base station, the mobile station before moving When an auxiliary base station has been requested to switch to the control station as a top priority candidate of a channel switching destination, the control station preferentially selects the general base station determined in advance from a positional relationship with a communicating base station. Base station selection method for cellular radiotelephone system
Law .