Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Reexamination Certificate
1999-12-29
2004-03-16
Tran, Sinh (Department: 2681)
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
C455S069000, C455S425000, C370S252000, C370S265000
Reexamination Certificate
active
06708042
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a communication method and a communication system for performing transmitting/receiving of signals between a base station and a plurality of mobile stations by wireless propagation, and particularly relates to a communication method and a communication system that enable the mobile station side to designate conditions of communications such as transmitting power, communication quality and the like when signals are transmitted.
In a large scale communication system, a service area has been heretofore formed of a plurality of wireless zones. Each respective wireless zone has a base station equipped with a transmitter and a receiver and communicates bidirectionally with a plurality of mobile stations, each equipped with a transmitter and a receiver, through wireless communication channels.
FIG. 8
is a schematic diagram showing a wireless zone according to a prior art communication system. In
FIG. 8
, a base station
1
acting as a relay station for communications and the like is set up in a wireless zone
3
, where mobile stations
51
,
52
, . . . ,
5
n such as portable telephones and the like for wireless communications with the base station
1
are located. The base station
1
is performing wireless communications with the mobile stations
51
,
52
, . . . ,
5
n with predetermined levels of transmitting power
61
, . . . ,
6
n and the communication area to be covered by the base station
1
is indicated by the wireless zone
3
. When wireless communications are performed between the base station
1
and a plurality of the mobile stations
51
,
52
, . . . ,
5
n, respectively as
FIG. 8
shows, transmitting power of signals has a great influence on communication quality. Therefore, many methods for controlling transmitting power have been adopted heretofore. A description is given to a prior art communication system employing a method of controlling transmitting power on the following.
The prior art communication system has transmitting frequencies for signals in wireless communications assigned to respective mobile stations
51
, . . . ,
5
n that are different from one another, and also transmitting powers
61
, . . . ,
6
n of signals between the base station
1
and the mobile stations
51
, . . . ,
5
n are set up in such a way that the mobile station located the farthest from the base station
1
(the mobile station
5
n located on the boundary of the wireless zone
3
in
FIG. 8
) is allowed to communicate with the base station
1
, and transmitting powers of all the mobile stations
51
,
5
n are made the same. Therefore, as the distance between the base station
1
and the respective mobile stations
51
, . . . ,
5
n becomes the smaller, the signal power level (signal energy level) of the received signal becomes the higher.
According to the prior art communication system as described in the above, as long as the mobile stations
51
, . . . ,
5
n are located within the wireless zone
3
of the base station
1
, it is made possible for wireless communications to be performed between the base station
1
and the respective mobile stations
51
, . . . ,
5
n.
Other prior art communication systems such as a spread spectrum communication system and the like use the same frequency as the signal propagating wave frequency in wireless communications throughout all the mobile stations
51
, . . . ,
5
n. Also, transmitting powers
61
, . . . ,
6
n of signals between the base station
1
and the respective mobile stations
51
, . . . ,
5
n are made different for each respective mobile station in order to have the signal power level of a signal received by the base station
1
from each of the mobile stations
51
, . . . ,
5
n made the same with one another. In other words, transmitting power of a signal between the base station
1
and any one of the mobile stations
51
, . . . ,
5
n is made proportionate to the distance between the base station
1
and the above one of the mobile stations
51
, . . . ,
5
n, thereby making it possible for the signal power level of a signal received by the base station
1
from any one of the mobile stations
51
, . . . ,
5
n to be the same with one another.
Accordingly, the prior art communication systems allow wireless communications to be performed among a plurality of mobile stations
51
, . . . ,
5
n by using the same frequency as the signal propagating wave frequency for all the mobile stations
51
, . . . ,
5
n.
A method for controlling transmitting power levels of signals in a communication system by assigning the same frequency to the propagating wave frequency for all the signals as described in the above is disclosed in a Japanese Patent Unexamined Publication numbered H9-326753. This method for controlling transmitting power levels allows a transmitting power level to be controlled up and down within a predetermined range according to the quality of received signals and also allows the charge management office to be informed of the intensity of received signals.
However, the prior art communication systems and the method for controlling transmitting power levels as disclosed by the Japanese Patent Unexamined Publication H9-326753 have a problem of inability to set up the transmitting power level, quality of communications and the like arbitrarily at the mobile station side. Therefore, in case where the information transmitted via wireless communications happens to be a computer program and the like, for example, the mobile station side (user side) has not been allowed to designate the conditions of wireless communications as needed according to the information to be transmitted as in the case where transmitting power, quality of communications and the like are to be enhanced when such information as a computer program add the like is transmitted via wireless communications and to be degraded when such information as voice data and the like is transmitted, for example.
In addition, in order to guarantee a high grade in communication quality, a transmitting power level exceeding a predetermined level has been maintained throughout a specific wireless zone, thereby keeping a given level of communication quality regardless the nature of information to be transmitted. In general, a transmitting power level is closely related to the level of fee charged to a mobile station (user) and for a certain user who is just involved with a voice data it may be ending up with a higher communication quality level than what is really needed, thereby causing sometimes a problem of bringing about an inappropriately high communication cost. On the other hand, with a communication system where the transmitting power level is set to an inadvertently low level, such provisions as sending the same data several times to ascertain the agreement of received data and the like, for example, are put in place in order to maintain a given level in communication quality for such information as a computer program and the like, thereby creating a problem of increasing communication costs due to prolonged communication time.
SUMMARY
The present invention deals with the problems as described in the above and the objective thereof is to provide a communication method and communication system that enable the establishment of the best conditions for communications according to the nature of information to be transferred and the communication environment by designating as needed at the mobile station side such conditions for wireless communications as a transmitting power level, a value of communication quality and the like.
The present invention also aims at providing a communication method and communication system to allow the communication fees to be determined according to the conditions of communications designated at the mobile station side in consideration of the nature of information to be transferred and also the optimization of communication costs in accordance with the communication conditions.
For achieving the foregoing objects, a communication method in a first exemplary embodiment of t
Afshar Kamran
Matsushita Electric - Industrial Co., Ltd.
Tran Sinh
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