JP2982374B2 - Car phone system - Google Patents

Abstract

PURPOSE:To minimize the degradation in the talking quality of a mobile station subjected to forced hand-over and to minimize the possibility of immediate requirement of the hand-over processing again by selecting an object of forced hand-over from a mobile station having a large difference from a reception electric field strength. CONSTITUTION:When a forced hand-over object request is received, a base station control circuit 11 reports a mobile station having a largest difference in a recording table in which the differences of reception electric field strength of radio waves from a base station in which the mobile station itself is resident so far and its adjacent base stations to an exchange 10 as the object of the forced hand-over and the exchange 10 implements required processing. Since a mobile station having a largest difference is selected as the object of the forced hand-over, a mobile station resident around the boundary of cells even among the mobile stations resident in a base station 11C is selected to be the object. For example, when the mobile stations 20, 21 are available of hand-over, the mobile station 21 resident in the vicinity of the boundary of cells is selected as the object by implementing the forced hand-over and it is avoided that the mobile station 20 is selected as the object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a mobile telephone system.

[0002]

2. Description of the Related Art Conventionally, in a car telephone system,
Of the mobile stations capable of handover, the candidates for forced handover were in ascending order of the used channel.

[0003]

However, in the case of forced handover, if the mobile stations that can be handed over are candidates in the order of the smallest number of the used channel, if the mobile station can be handed over barely, The call quality of the mobile station may be degraded and a handover process for the mobile station may be needed immediately.

[0004]

The mobile telephone system of the present invention has a function of calculating the difference between the received electric field strength of the base station and the received electric field strength of the adjacent base station for each mobile station, and recording and holding the difference. The mobile station having the largest difference among the mobile stations capable of handover is provided as a candidate for forced handover in the base station controller.

[0005]

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

Referring to FIG. 1 showing an embodiment of the present invention, an exchange 10 controls base station controllers 11 and 12,
A handover process and a control handover process are performed. The base station controller 11 controls the base stations 11A to 11I, receives the received field strength measurement data of the base station for each mobile station transmitted from the base stations 11A to 11I, calculates the difference from the adjacent base station, and It has the function of recording and holding. The base station controller 12 controls the base stations 12A to 12K, receives the received field strength measurement data of the mobile station type base station transmitted from the base stations 12A to 12K, calculates the difference from the adjacent base station, and It has the function of recording and holding. Base station 11A
11I and 12A to 12K relay the received field strength data transmitted from the mobile station to the base station controllers 11 and 12. The mobile station measures the received electric field strength from the base station where the mobile station is located, identifies the adjacent base station, measures the received electric field strength, and periodically reports the measurement result to the base station.

Next, the operation of the strength handover process will be described. It is assumed that traffic overload has occurred in the base station 11C. The exchange 10 is a base station 11
When it is detected in C that a traffic overload has occurred, a forced handover candidate request is sent to the base station controller 11. Upon receiving the forced handover candidate request, the base station controller 11 records the difference between the received electric field strength of the radio wave from the base station where the mobile station is located and the received electric field strength of the radio wave from the adjacent base station for each mobile station. Referring to the table, the mobile station having the largest difference among them is reported to the exchange 10 as a candidate for forced handover. Exchange 1
If the value is 0, the mobile station performs a forced handover process. Since the candidate for the forced handover selects the mobile station with the largest difference between the mobile stations capable of handover,
Among the mobile stations at the base station 11C, mobile stations near the cell boundary are candidates. If the mobile station 20 and the mobile station 21 can perform handover in FIG. 1, if this forced handover is performed, the mobile station 21 closer to the cell boundary is selected as a candidate, and the mobile station 20 becomes a candidate. It will not be. Therefore, the possibility that a mobile station whose path quality is deteriorated due to a forced handover is reduced,
It is less likely that the mobile station that has been subjected to the forced handover will need to perform a handover process immediately after the forced handover.

[0008]

As described above, according to the present invention, the degradation of the communication quality of the mobile station which is forced to be handed over is minimized by selecting the candidate for the forced handover from the one having a large difference in the received electric field strength. , And the possibility that the handover process is immediately required again for the mobile station that has handed over is minimized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Switch 11 Base station controller 12 Base station controller 11A-11I Base station 12A-12K Base station 20, 21 Mobile station

Claims (1)

(57) [Claims] A base station controller has a function of calculating a difference between a received electric field strength of its own base station and a received electric field strength of an adjacent base station for each mobile station, and recording and holding the difference. A mobile telephone system characterized in that mobile stations having the largest difference among the stations are candidates for forced handover.