Method and an apparatus for positioning system assisted cellular radiotelephone handoff and dropoff

A communication system, comprising:

• one or more radiotelephones;
• a plurality of base stations for transmitting communication signals to and receiving communication signals from the radiotelephones;
• a positioning system in at least one of the radiotelephones for determining the spatial position of the radiotelephone;
• wherein one of the base stations performs a dropoff of the radiotelephone containing the positioning system when the quality of the radiotelephone communication signal is predicted to be less than a predetermined value based on the spatial position of the radiotelephone, the radiotelephone being dropped from the communication system when the base station performs the dropoff;
• the positioning system uses GPS satellite signals to determine spatial position of the radiotelephone further comprises:
• a data storage area for storing ephemeris data of the GPS satellites;
• a clock synchronized with one of the GPS satellites;
• a code storage area including software programs;
• a microprocessor for executing the software programs;
• and
• a detachable GPS receiver connected to the radiotelephone.

In a communication network including a radiotelephone and a plurality of base stations, a method for performing radiotelephone handoff and dropoff comprising the steps of:

• determining the spatial position of the radiotelephone using a positioning system;
• determining a distance between the radiotelephone and a location where the quality level of a radiotelephone communications signal is predicted to be less than a predetermined value, based upon the spatial position of the radiotelephone;
• comparing the determined distance with a distance limit to predict a quality level of a radiotelephone communication signal based on the spatial position of the radiotelephone;
• performing a dropoff of the radiotelephone from the communication network when the quality level of the radiotelephone communication signal is predicted to be less than a first predetermined value;
• and
• performing a handoff of the radiotelephone when the quality of the radiotelephone communication signal is predicted to be less than a second predetermined value.

A radiotelephone for use in a communications system, comprising:

• a cellular communications unit for transmitting a cellular communication signal with at least one base station;
• a global positioning system electrically coupled to the cellular communications unit, for determining the spatial position of the radiotelephone;
• positioning system memory for storing data indicating an ephemeris of a plurality of satellites;
• the cellular communications unit further comprises a central processing unit (CPU), a memory electrically coupled to the CPU, and software programs stored on the memory and executable by the CPU to support a communication protocol between the radiotelephone and the at least one base station;
• and
• the at least one base station is capable of performing a drop-off of the radiotelephone when the quality of the radiotelephone communication signal is predicted to be less than a predetermined value based upon the spatial position of the radiotelephone.

A radiotelephone for use in a communications system, comprising:

• first means for transmitting a cellular communication signal to at least one base station;
• second means for determining a spatial position of the radiotelephone;
• third means for storing data indicating an ephemeris of a plurality of satellites;
• the first means further comprises a support means to support a communication protocol between the radiotelephone and the at least one base station;
• and
• the at least one base station is capable of performing a drop-off of the radiotelephone when the quality of the radiotelephone communication signal is predicted to be less than a predetermined value based upon the spatial position of the radiotelephone.

A method for controlling communications of a radiotelephone with at least one base station, comprising the steps of:

• establishing a cellular communications link with at least one base station;
• determining a spatial position of the radiotelephone, wherein the spatial position is employed to control a state of the cellular communications link with the at least one base station;
• storing data indicating an ephemeris of a plurality of satellites into a storage area within the radiotelephone;
• receiving a base station position and a distance limit from the at least one base station;
• determining a distance between the radiotelephone and a location where the quality level of the cellular communications link is predicted to be less than a predetermined value, based upon the spatial position of the radiotelephone;
• comparing the determined distance with the distance limit to determine whether the radiotelephone is a candidate for a handoff;
• and
• notifying the at least one base station that the radiotelephone is a candidate for handoff.