JPH04344723A - Automobile telephone 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 1. Field of the Invention The present invention relates to a car telephone system.

0002

[Prior Art] Conventionally, in a car telephone system,
Among the mobile stations that are available for handover, the mobile stations are candidates for forced handover in descending order of the number of used channels.

0003

[Problem to be Solved by the Invention] However, when performing a forced handover, if candidates are selected in descending order of channel numbers among mobile stations that can be handed over, if the mobile station is just barely able to be handed over, This may degrade the call quality of the mobile station and may require immediate handover processing for the mobile station.

0004

[Means for Solving the Problems] The mobile telephone system of the present invention has a function of calculating the difference between the received electric field strength of its own base station and the received electric field strength of an adjacent base station for each mobile station, and recording and retaining the difference. It is provided in the base station control device, and among the mobile stations that can be handed over, the mobile station with the largest difference is selected as a candidate for forced handover.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained 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 and performs handover processing and controlled handover processing. The base station control device 11 controls the base stations 11A to 11I,
It has a function of receiving received field strength measurement data of the base station for each mobile station sent from the base stations 11A to 11I, calculating the difference with the adjacent base station, and storing the result. A base station control device 12 controls base stations 12A to 12K, and base station 1
It has a function of receiving received field strength measurement data of mobile station type base stations sent from 2A to 12K, calculating the difference with adjacent base stations, and storing the result. Base station 11A-1
1I, 12A to 12K relay received field strength data sent from the mobile station to base station controllers 11 and 12. A mobile station measures the received field strength from the base station where it is located, identifies adjacent base stations, measures their received field strength, and periodically reports the measurement results to the base station.

Next, the operation of strong handover processing will be explained. Assume that a traffic overload occurs at the base station 11C. The exchange 10 is a base station 11
When detecting that traffic overload has occurred in C, a forced handover candidate request is sent to the base station control device 11. When the base station control device 11 receives the forced handover candidate request, it records the difference between the received field strength of the radio waves from the base station where the mobile station is located and the received field strength of the radio waves from the adjacent base station for each mobile station. With reference to the table, the mobile station with the largest difference is reported to the exchange 10 as a candidate for forced handover. Exchange 1
At 0, forced handover processing is performed for that mobile station. The candidate for forced handover is the one with the largest difference among the mobile stations that can be handovered, so
Among the mobile stations located at the base station 11C, mobile stations located closer to the cell boundary become candidates. If handover is possible between mobile station 20 and mobile station 21 in FIG. 1, if this forced handover is performed, mobile station 21 that is closer to the cell boundary will be selected as a candidate, This will no longer be the case. Therefore, the possibility of a mobile station having poor path quality due to forced handover is reduced.
It is also less likely that the mobile station forced to handover will need handover processing immediately after the forced handover.

[0008]

[Effects of the Invention] As explained above, according to the present invention, by selecting candidates for forced handover in descending order of the difference in received field strength, the deterioration in speech quality of mobile stations subjected to forced handover can be minimized. This also minimizes the possibility that a mobile station that has been handed over will immediately need handover processing again.

[Brief explanation of drawings]

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

[Explanation of symbols]

10　　　　　Exchange machine 11 Base station control device 12 Base station control device 11A-11I Base station 12A~12K Base station 20, 21 Mobile station

Claims (1)

[Claims] Claim 1: A base station control device is provided with a function for calculating the difference between the received field strength of its own base station and the received field strength of an adjacent base station for each mobile station and records and retains the difference, and mobile station capable of handover is provided. A mobile telephone system characterized in that a mobile station having the largest difference among the stations is selected as a candidate for forced handover.