Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-02-05
2001-10-30
Trost, William (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S441000, C455S437000, C455S574000, C455S434000, C455S515000, C455S343200, C455S423000, C455S067150, C455S226100, C455S226200, C370S337000, C370S348000, C370S347000
Reexamination Certificate
active
06311059
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mobile radio station such as a GSM (Global System for Mobile communication) mobile phone, and particularly to a radio base station monitoring control by the mobile radio station.
2. Description of the Related Art
In the GSM system, each radio base station reserves four TDMA frames every n multiframes as a paging channel. The value of n can be set for a particular radio base station to any value from 2 to 9. A single block of paging channel frames are long enough for the mobile radio station to listen to its current radio base station for any incoming call and to receive from two neighboring radio base stations in each frame and measure the signal strengths thereof. Thus the signal strength received from eight neighboring radio base stations can be monitored in every n multi-frame.
If two monitor operations are performed in every paging channel TDMA frame a considerable amount of power will be wasted, if the mobile radio station is, for example, at the center of a cell where it is unlikely that any hand-off to a neighboring radio base station will be required imminently.
On the other hand, although it is simple to arrange that fewer monitor operations are performed, this will have the effect of degrading cell reselection performance.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a mobile radio station for use in a mobile radio network in which the rate at which neighboring radio base stations are monitored can be reduced for power saving purposes without significantly degrading cell reselection performance.
The reception field strengths of a current cell and of signals transmitted from radio base stations neighboring the current cell are measured. If the reception field strength of a current cell is less than a first threshold that has been previously determined, a rate of decrease of reception field strength of the current cell is determined. If the rate of decrease exceeds a second threshold, reception field strengths of signals transmitted from a maximum number of previously determined radio base stations from among neighboring radio base stations are measured. If the reception field strength of a current cell is over the first threshold or if the rate of decrease is under the second threshold, the reception field strengths of signals transmitted from a number of radio base stations less than the maximum number from among neighboring radio base station are measured.
The above and other objects, features, and advantages of the present invention will become apparent from the following description based on the accompanying drawings which illustrate examples of preferred embodiments of the present invention.
REFERENCES:
patent: 5448569 (1995-09-01), Huang et al.
patent: 5711005 (1998-01-01), Farrag
patent: 5722072 (1998-02-01), Crichton et al.
patent: 6044272 (2000-03-01), Kobylinski et al.
patent: 2 305 825 (1997-04-01), None
Ferguson Keith
NEC Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
Trost William
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