Multiplex communications – Duplex – Communication over free space
Reexamination Certificate
1997-11-13
2001-03-27
Nguyen, Chau (Department: 2663)
Multiplex communications
Duplex
Communication over free space
C370S468000, C370S335000
Reexamination Certificate
active
06208624
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scheme for paging in a mobile communication system having a plurality of base stations provided in respective cells, where each base station is transmitting a paging channel on which a paging signal for each mobile station is transmitted at intermittent timings such that each mobile station judges a presence or absence of a paging signal for the own station by receiving the paging channel at these intermittent timings.
2. Description of the Background Art
In the cellular mobile communication system, at a time of call termination for a mobile station located within a cell of a base station, the base station carries out the paging with respect to the mobile station by using a downlink radio channel called paging channel.
Usually, each frame of this paging channel (PCH) is divided along the time axis into a plurality of time-slots (TS) as shown in
FIG. 1
, where which time-slot of the paging channel frame is to be used for the paging with respect to which mobile station is determined in advance. Consequently, while waiting for a call to the own station, it suffices for the mobile station to receive only the specific time-slot of the paging channel frame intermittently and there is no need to constantly receive the paging channel.
By increasing a number of time-slots to be used, it is possible to reduce a rate (referred hereafter as an intermittent ratio) of a time period for which the mobile station actually receives the paging channel with respect to the entire time period of the paging channel frame, and consequently it is possible to reduce the power consumption at a time of call waiting by the mobile station considerably compared with a case of constantly receiving the paging channel.
In an example shown in
FIG. 1
, each frame of the paging channel is divided into right time-slots, and the mobile station receives only one time-slot (TS
3
in an example of
FIG. 1
) among them at a time of call waiting. Consequently, in this example, the intermittent ratio is 1/8 so that the power consumption of the mobile station at a time of call waiting can be reduced to 1/8.
Now, in the conventional mobile communication system, the intermittent ratio has been reduced by increasing a number of time-slots. However, when a number of time-slots is increased, the paging interval also increases as shown in
FIG. 2
, and consequently, an average time required for the paging is also increased so that there has been a limit to an extent by which the intermittent ratio can be reduced by the increase of a number of time-slots. In an example shown in
FIG. 2
, a number of time-slots is increased to twelve from eight used in
FIG. 1
, so that the intermittent ratio is reduced from 1/8 to 1/12, but the average time required for the paging is also increased accordingly.
It is also possible to reduce the paging interval by reducing a data amount necessary for the paging and thereby reducing a unit time-slot duration, but there is also a limit to an extent by which the data amount necessary for the paging can be reduced, so that there is also a limit to an extent by which the intermittent ratio can be reduced in this way.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a paging scheme for a mobile communication system which is capable of suppressing the power consumption of the mobile station by reducing the intermittent ratio while keeping an average time required for the paging shorter than a case of merely increasing a number of time-slots. In short, this is realized in the present invention by using a higher data transmission rate for the paging channel so as to reduce a unit time-slot duration and then increasing a number of time-slots.
According to one aspect of the present invention there is provided a method of paging in a mobile communication system having a plurality of base stations provided in respective cells and mobile stations, comprising the steps of: transmitting from each base station radio channels in a plurality of different data transmission rates, the radio channels including a paging channel on which a paging signal for each mobile station is transmitted at intermittent timings, the paging channel having a data transmission rate which is higher than a required paging channel rate of the mobile communication system, so as to shorten a transmission time of the paging signal for each mobile station; and judging at each mobile station a presence or absence of the paging signal for said each mobile station by receiving the paging channel at said intermittent timings.
According to another aspect of the present invention there is provided a base station device for use in a mobile communication system having a plurality of base stations provided in respective cells and mobile stations, comprising: a communication channel transmission unit for transmitting communication channels; and a control channel transmission unit for transmitting control channels in a plurality of different data transmission rates, the control channels including a paging channel on which a paging signal for each mobile station is transmitted at intermittent timings, the paging channel having a data transmission rate which is higher than a required paging channel rate of the mobile communication system, so as to shorten a transmission time of the paging signal for each mobile station.
According to another aspect of the present invention there is provided a mobile station device for use in a mobile communication system having a plurality of base stations provided in respective cells and mobile stations, comprising: a receiving unit for receiving signals from each base station, including a paging signal for each mobile station transmitted on a paging channel at intermittent timings, the paging channel being transmitted by each base station at a data transmission rate which is higher than a required paging channel rate of the mobile communication system; and a control unit for judging a presence or absence of the paging signal for said mobile station device by controlling the receiving unit to receive the paging channel at said intermittent timings according to the data transmission rate of the paging channel.
According to another aspect of the present invention there is provided a method of paging in a mobile communication system having a plurality of base stations provided in respective cells and mobile stations, comprising the steps of: transmitting from each base station radio channels in a plurality of different data transmission rates, the radio channels including a paging channel on which a paging signal for each mobile station is transmitted at intermittent timings, the paging channel having a data transmission rate which is variable; and judging at each mobile station a presence or absence of the paging signal for said each mobile station by receiving the paging channel at said intermittent timings.
According to another aspect of the present invention there is provided a base station device for use in a mobile communication system having a plurality of base stations provided in respective cells and mobile stations, comprising: a communication channel transmission unit for transmitting communication channels; and a control channel transmission unit for transmitting control channels in a plurality of different data transmission rates, the control channels including a paging channel on which a paging signal for each mobile station is transmitted at intermittent timings, the paging channel having a data transmission rate which is variable.
According to another aspect of the present invention there is provided a mobile station device for use in a mobile communication system having a plurality of base stations provided in respective cells and mobile stations, comprising: a receiving unit for receiving signals from each base station, including a paging signal for each mobile station transmitted on a paging channel at intermittent timings, the paging channel being transmitted by each base stati
Nakamura Takehiro
Onoe Seizo
Tanno Motohiro
Lee Chiho Andrew
Nguyen Chau
NTT Mobile Communications Network Inc.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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