Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-04-08
2001-12-11
Chang, Vivian (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S432300
Reexamination Certificate
active
06330446
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a power-saving method of controlling registration in mobile communication systems such as, for example, code division multiple access (CDMA) cellular telephone systems.
The mobile terminals in a mobile communication system register their location with the system from time to time, so that the system can page them quickly when the need arises. For CDMA cellular telephone systems, Interim Standard IS-95 of the Telecommunication Industries Association specifies, among other forms of registration control, a timer-based scheme in which an idle mobile terminal sends a registration message to the system at regular intervals, which are designated by the system. The registration message contains information that the system can analyze to determine the location of the mobile terminal. The system stores the mobile terminal's location in a data base, which is updated as new registration messages arrive.
A problem with this registration control scheme is that while standing by to receive calls, a mobile terminal continues to send registration messages at the designated regular intervals, even if the mobile terminal is not actually moving. Since the registration messages are transmitted at comparatively high power, much power is dissipated in this way, causing unnecessary battery drain and shortening the time the mobile can continue operating in standby. System resources are also consumed in unnecessary data-base updates.
This problem is not limited to CDMA cellular telephone systems; it can occur in any type of mobile communication system that performs timer-based location registration.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to reduce the power dissipated by mobile terminals in performing location registration in a mobile communication system.
A further object is to reduce the usage of system resources in location registration updates.
The invented method of registration control in a mobile communication system comprises the steps of:
determining the velocity of a mobile terminal; and
adjusting the registration interval of the mobile terminal according to its velocity.
These steps can be performed by the system, by the mobile terminal, or by both. For example, the mobile terminal can determine its own velocity, and the system can adjust the registration interval in response to a request sent by the mobile terminal when the registration interval is inappropriate for the velocity.
The velocity of a mobile terminal can be determined in various ways: for example, from positional information provided by the base stations within range of the mobile terminal, or by sensing the Doppler shift in a carrier signal frequency.
The invention also provides a mobile terminal, a location registration apparatus, and a mobile communication system employing the invented method of registration control.
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Appiah Charles N.
Chang Vivian
Gluck Jeffrey W.
OKI Electric Industry Co., Ltd.
Sartori Michael A.
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