Handoff control with a pilot used in a cell of a neighboring cell in a CDMA mobile communication network on a service frequency of the neighboring cell
First Claim
1. A handoff control method for use in a code division multiple access mobile communication network comprising a control station and first and second base stations connected to said control station and having a service area in which a mobile unit is movable and which is divided into a plurality of cells including first and second cells neighboring each other, said handoff control method comprising the steps of assigning first and second service frequencies to said first and said second base stations for traffic communication with said mobile unit, while said mobile unit is in said first and said second cells, detecting necessity of handoff between said first and said second service frequencies, and dealing with said handoff when said necessity is detected, wherein:
- said assigning step assigns said second service frequency additionally to said first base station for an alternative use in said traffic communication and said first service frequency to said second base station for transmitting only a pilot signal;
said dealing step dealing with, while said mobile unit moves in said first cell towards said second cell during the traffic communication with said first base station on said first service frequency, handoff from said first service frequency to said second service frequency when said necessity is detected.
1 Assignment
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Accused Products
Abstract
To expedite handoff control while a mobile unit moves between first and neighboring second cells, A and B frequencies are assigned for traffic communication to a first base station and only B frequency is assigned for traffic communication to a second base station, and both of the base stations are connected to a control station, where the first base station is assigned to the first cell and the second base station is assigned to the second cell. The mobile unit has been assigned A frequency in the first base station, and the second base station is accompanied by a pilot transmitting device for transmitting only a pilot signal on the A frequency. As soon as it is informed of deterioration in a field intensity of the frequency at the mobile unit together with pilot information specific to the pilot signal from the first base station, the control station makes a determination that the mobile unit is approaching the second base station, and deals with a handoff from the A frequency to the B frequency.
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Citations
20 Claims
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1. A handoff control method for use in a code division multiple access mobile communication network comprising a control station and first and second base stations connected to said control station and having a service area in which a mobile unit is movable and which is divided into a plurality of cells including first and second cells neighboring each other, said handoff control method comprising the steps of assigning first and second service frequencies to said first and said second base stations for traffic communication with said mobile unit, while said mobile unit is in said first and said second cells, detecting necessity of handoff between said first and said second service frequencies, and dealing with said handoff when said necessity is detected, wherein:
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said assigning step assigns said second service frequency additionally to said first base station for an alternative use in said traffic communication and said first service frequency to said second base station for transmitting only a pilot signal; said dealing step dealing with, while said mobile unit moves in said first cell towards said second cell during the traffic communication with said first base station on said first service frequency, handoff from said first service frequency to said second service frequency when said necessity is detected. - View Dependent Claims (2, 3)
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4. A handoff control method for use in a combination of a code division multiple access mobile communication network and a neighboring mobile communication network, said combination comprising a control station and first and second base stations connected to said control station and having a common service area in which a mobile unit is movable and which is divided into a plurality of cells including a first cell of said neighboring mobile communication network and a second cell neighboring said first cell in said code division multiple access mobile communication network, said handoff control method comprising the steps of assigning first and second service frequencies to said first and said second base stations for traffic communication with said mobile unit, while said mobile unit is in said first and said second cells, detecting necessity of handoff between said first and said second service frequencies, and dealing with said handoff when said necessity is detected, wherein:
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said assigning step assigns said second service frequency additionally to said first base station for an alternative use in said traffic communication and said first service frequency to said second base station for transmitting only a pilot signal; said dealing step dealing with, while said mobile unit moves in said first cell towards said second cell during the traffic communication with said first base station on said first service frequency, handoff from said first service frequency to said second service frequency when said necessity is detected. - View Dependent Claims (5, 6, 7)
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8. A handoff control system for use in a code division multiple access mobile communication network comprising a control station and first and second base stations connected to said control station and having a service area in which a mobile unit is movable and which is divided into a plurality of cells including first and second cells neighboring each other with said first and said second base stations assigned with first and second service frequencies for traffic communication with said mobile unit while said mobile unit is in said first and said second cells, said control station comprising a control device for detecting necessity of handoff between said first and said second service frequencies and for dealing with said handoff when said necessity is detected, wherein:
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said first base station is additionally assigned with said second service frequency for an alternative use in said traffic communication; said second base station comprising a pilot transmitting device for transmitting only a pilot signal on said first service frequency; said control device dealing with, when said necessity is detected while said mobile unit moves in said first cell towards said second cell during the traffic communication with said first base station on said first service frequency, handoff from said first service frequency to said second service frequency. - View Dependent Claims (9, 10)
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11. A handoff control system for use in a combination of a code division multiple access mobile communication network and a neighboring mobile communication network, said combination comprising a control station and first and second base stations connected to said control station and having a common service area in which a mobile unit is movable and which is divided into a plurality of cells including a first cell of said neighboring mobile communication network and a second cell neighboring said first cell in said code division multiple access mobile communication network with said first and second base stations assigned with first and second service frequencies for traffic communication with said mobile unit while said mobile unit is in said first and said second cells, said control station comprising a control device for detecting necessity of handoff between said first and said second service frequencies and for dealing with said handoff when said necessity is detected, wherein:
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said first base station is additionally assigned with said second service frequency for an alternative use in said traffic communication; said second base station comprising a pilot transmitting device for transmitting only a pilot signal on said first service frequency; said control device dealing with, when said necessity is detected while said mobile unit moves in said first cell towards said second cell during the traffic communication with said first base station on said first service frequency, handoff from said first service frequency to said second service frequency. - View Dependent Claims (12, 13, 14)
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15. A control station for use in a code division multiple access mobile communication network comprising first and second base stations connected to said control station and having a service area in which a mobile unit is movable and which is divided into a plurality of cells including first and second cells neighboring each other with said first and said second base stations assigned with first and second service frequencies for traffic communication with said mobile unit while said mobile unit is in said first and said second cells, said control station comprising a control device for detecting necessity of handoff between said first and said second service frequencies and for dealing with said handoff when said necessity is detected, wherein:
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said first base station is additionally assigned with said second service frequency for an alternative use in said traffic communication; said control device dealing with, when said necessity is detected while said mobile unit moves in said first cell towards said second cell during the traffic communication with said first base station on said first service frequency, handoff from said first service frequency to said second service frequency. - View Dependent Claims (16, 17)
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18. A control station for use in a combination of a code division multiple access mobile communication network and a neighboring mobile communication network, said combination comprising first and second base stations connected to said control station and having a common service area in which a mobile unit is movable and which is divided into a plurality of cells including a first cell of said neighboring mobile communication network and a second cell neighboring said first cell in said code division multiple access mobile communication network with said first and said second base stations assigned with first and second service frequencies for traffic communication with said mobile unit while said mobile unit is in said first and said second cells, said control station comprising a control device for detecting necessity of handoff between said first and said second service frequencies and for dealing with said handoff when said necessity is detected, wherein:
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said first base station is additionally assigned with said second service frequency for an alternative use in said traffic communication; said second base station comprising a pilot transmitting device for transmitting only a pilot signal on said first service frequency; said control device dealing with, when said necessity is detected while said mobile unit moves in said first cell towards said second cell during the traffic communication with said first base station on said first service frequency, handoff from said first service frequency to said second service frequency. - View Dependent Claims (19, 20)
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Specification