JP2586335B2 - Handoff method for cellular telephone system. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellular telephone system, and more particularly to a handoff system for a cellular telephone system which switches a communication channel as a mobile unit moves between cells.

[0002]

2. Description of the Related Art In a cellular telephone system of this type comprising a mobile station, a radio base station and a control station, a control station transmits a call to a mobile station from a cell area where a base station A is located. When moving to a cell area, channel switching from the radio channel of the base station A to the radio channel of the base station B, that is, handoff is required. conventionally,
When such a handoff is performed, the wireless channels of all the wireless base stations adjacent to the wireless base station in the cell area where the mobile station exists are set as handoff candidates. Then, in order to determine a handoff destination base station from among these candidates, the control station issues an electric field measurement request of the corresponding mobile station to all adjacent base stations, and the electric field measured in response to this request. The measurement result data is received from each base station, and a handoff destination base station is determined based on the received data.

[0003]

In such a cellular telephone system, an electric field measurement request is transmitted to a radio base station which is not a handoff destination in the moving direction of the mobile station, and the measurement result is received. However, the control station takes a long time to perform a handoff process such as an electric field measurement request process, a measurement result reception wait process, a reception result determination process, and the like, resulting in an increase in the load on the control station.

[0004] Some mobile devices can detect the position where they are currently located, but the detected position information is used only in the mobile device that is only displayed in the mobile device. Therefore, no attempt has been made to reduce the load on the control station by performing the electric field measurement only on the cell area where the mobile station needs to move by using the position information.

Accordingly, an object of the present invention is to reduce the handoff processing time in the control station and reduce the load on the control station.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a plurality of radio base stations each having a unique cell area, and moves between each cell area by being wirelessly connected to the radio base station. Means for detecting a moving direction of a mobile station in a cellular telephone system comprising a mobile station to be connected and a control station connected to each wireless base station by a wired line, and a cell area corresponding to a detection output of the detecting section. And an electric field measurement requesting means for making an electric field measurement request, and a handoff executing means for switching a channel to a radio channel in a cell area having a strong electric field measured based on the electric field measurement request. Further, as the detection means, a position detector for detecting the current position and the traveling direction of the mobile device is provided in the mobile device, and a map data storage unit that stores map data covering all cell areas of the cellular telephone system, A mobile station position information storage unit for storing the position information and the traveling direction information detected by the position detector, and a mobile unit traveling direction determining unit are provided in the control station, and the mobile unit direction determining unit is provided in a cell area where the mobile unit actually exists. The cell area to which the mobile device moves is detected by referring to the map data based on the position information and the traveling direction information when the wireless base station is notified of the deterioration of the electric field strength due to the movement of the mobile device. Things.

[0007]

The electric field is measured for each cell area corresponding to the moving direction of the mobile station, and the handoff is executed for the cell area corresponding to the measured electric field intensity. As a result, the number of cell area candidates at the handoff destination can be reduced,
The handoff processing time in the control station is reduced, and the load on the control station is reduced. Further, the mobile station traveling direction determination unit provided in the control station as a detecting means, when notified of the deterioration of the electric field strength accompanying the movement of the mobile station from the radio base station in the cell area where the mobile station actually exists, the mobile station The cell area to which the mobile device moves is detected by referring to the map data based on the position information and the traveling direction information detected by the position detector.
As a result, the cell area to which the mobile device moves can be accurately detected.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention.
1 shows an example of a cellular telephone system. In the figure, 1 is a mobile station, 2 is a control station, 3 to 9 are radio base stations connected to the control station 2 by a wired line and connected to the mobile station 1 by a radio line, and 10 to 16 are radio stations. Base stations 3 to 9
Is a cell area indicating a wireless zone.

In the cellular telephone system configured as described above, when the mobile station 1 during a call moves from one cell area to another cell area, the control station 2 switches a call channel called handoff. There is a need. In such a case, if the control station 2 causes the radio base stations in all adjacent cell areas to measure the electric field strength of the mobile station 1 and executes the handoff based on the measurement result, the handoff process takes a long time and the control station 2 Load increases. For this reason, the mobile station 1 and the control station 2 are configured as shown in FIG. 2 to be described later, and the electric field strength request of the mobile station 1 is transmitted only in a necessary cell area, thereby reducing the load on the control station 2.

FIG. 2A is a block diagram showing a configuration of the mobile device 1. The mobile device 1 includes a mobile device main body 17 and a position detector 18 for detecting the position of the mobile device 1. The mobile device main body 17 and the position detector 18 have antennas AT1 and A, respectively.
T2 is connected. Here, when the position and the traveling direction of the mobile device 1 are detected by the position detector 18, these pieces of information are sent to the mobile device main body 17. The mobile device body 17
While transmitting the position information and the traveling direction information to the nearest wireless base station via a wireless line via the antenna AT1,
The nearest base station transmits such information to the control station 2 via a wired line.

FIG. 2B is a diagram showing functional blocks of the control station 2 for receiving the position information and the traveling direction information transmitted from the mobile device 1, and shows the received position and traveling direction of the mobile device 1. Each piece of information is stored in the mobile device position information storage unit 21. Further, the control station 2 is provided with a map data storage unit 22 for storing map data of all cell areas covered by the cellular telephone system.

When the control station 2 receives the position and traveling direction information of the mobile unit 1, it stores it in the mobile unit position information storage unit 21 and based on the received information, the map data storage unit 22. To which cell area the mobile device 1 is moving with reference to the map data. Then, a request for measuring the electric field of the mobile station 1 is sent to the wireless base station in the detected cell area. Thereafter, the control station 2 performs handoff based on the electric field measurement result from the wireless base station that has issued the electric field measurement request. As a result, the handoff processing time in the control station 2 is reduced, and the load on the control station 2 can be reduced.

Next, the operation of the main part of the present invention will be described in more detail with reference to FIGS. In FIG. 1, cell area 1
It is assumed that the mobile device 1 existing at 0 is moving in the direction of the cell area 14 or the cell area 15. At this time, the radio base station 3 arranged in the cell area 10 detects the deterioration of the intensity of the radio wave from the mobile device 1 and reports the deterioration to the control station 2.

On the basis of the deterioration report from the radio base station 3, the control station 2 makes an electric field measurement request of the mobile station 1 to the radio base stations arranged in the adjacent cell area.
In this case, the mobile unit traveling direction determination unit 23 of the control station 2 stores the map data based on the mobile unit position information and the traveling direction information already received from the mobile unit 1 and stored in the mobile unit position information storage unit 21. With reference to the data of the unit 22, it is determined and detected that the mobile device 1 is moving in the direction of the cell area 14 or the cell area 15. This mobile device traveling direction determination unit 2
Based on the detection result of No. 3, the control station 2 issues an electric field measurement request of the mobile device 1 only to the radio base station 7 disposed in the cell area 14 and the radio base station 8 disposed in the cell area 15. .

After that, the control station 2 receives the data of the measurement result based on the electric field measurement request from the radio base station 7 and the radio base station 8. Then, based on these electric field measurement results, handoff is performed to the wireless base station having the stronger electric field. As described above, when performing the handoff, the mobile device 1
Since an electric field measurement request is made only for the traveling direction cell area and handoff is performed based on the measurement result,
Since all the adjacent cell areas are not subject to the electric field measurement, the handoff processing time of the control station 2 and its load can be reduced.

[0016]

As described above, according to the present invention, the direction of movement of a mobile station is detected, an electric field measurement request is made to each cell area according to the detected output, and the measurement is performed based on the electric field measurement request. Since the handoff to switch the channel to the radio channel of the cell area according to the strength of the electric field is performed, the number of candidates for the cell area of the handoff destination can be reduced, and thus the handoff processing time in the control station is reduced, There is an effect that the load on the control station can be reduced. Further, the mobile station traveling direction determination unit provided in the control station as a detecting means, when notified of the deterioration of the electric field strength accompanying the movement of the mobile station from the radio base station in the cell area where the mobile station actually exists, the mobile station Since the moving direction of the mobile device is detected by referring to the map data based on the position information and the traveling direction information detected by the position detecting device, the cell area to which the mobile device moves can be accurately detected. This has the effect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a cellular telephone system.

FIG. 2 is a block diagram (FIG. 2 (a)) of a mobile device constituting the above system and a functional block diagram of a control station (FIG. 2).
(B)).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mobile station, 2 ... Control station, 3-9 ... Radio base station, 10
16: cell area, 17: mobile unit body, 18: position detector, 21: mobile unit position information storage unit, 22: map data storage unit, 23: mobile unit traveling direction determination unit.

Claims (2)

(57) [Claims] 1. A plurality of radio base stations each having a unique cell area, a mobile station wirelessly connected to the radio base station and moving between cell areas, and connected to each of the radio base stations by a wire line. A cellular telephone system comprising a control station, a detecting unit for detecting a moving direction of the mobile station, an electric field measuring requesting unit for making an electric field measuring request to each cell area according to a detection output of the detecting unit, A handoff executing means for switching a channel to a radio channel in a cell area having a strong electric field measured based on the electric field measurement request. 2. The cellular phone system according to claim 1, wherein the detecting means comprises a position detector for detecting a current position and a traveling direction of the mobile device, and the whole of the cellular telephone system. A control station comprising: a map data storage unit for storing map data covering the cell area; a mobile station position information storage unit for storing position information and traveling direction information detected by the position detector; and a mobile station traveling direction determination unit. In preparation, the mobile device direction determination unit is based on the position information and the traveling direction information when notified of the deterioration of the electric field strength due to the movement of the mobile device from the radio base station in the cell area where the mobile device actually exists. A handoff method for a cellular telephone system, wherein a cell area in which a mobile device moves is detected by referring to map data.