Telecommunications – Transmitter – Power control – power supply – or bias voltage supply
Reexamination Certificate
1999-04-06
2002-04-23
To, Doris H. (Department: 2682)
Telecommunications
Transmitter
Power control, power supply, or bias voltage supply
C455S552100, C455S069000, C455S550100
Reexamination Certificate
active
06377785
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a portable telephone set which is subject to transmission power control, and a communications system incorporating such a portable telephone set.
2. Description of the Related Art
In a communication system which employs a code division multiple access (CDMA) process for radio communications, a number of base stations and mobile stations communicate with each other in respective established links at the same frequency. The received power (desired power) of a signal in a certain link acts as interference power that disturbs other links. In an uplink transmission where a mobile station transmits a signal and a base station receives the transmitted signal, when the desired power exceeds a predetermined power level, the interference power increases, thus reducing the link capacity.
To prevent the above phenomenon from occurring, it is necessary to strictly control the transmission power of mobile stations. According to one uplink transmission power control process, the desired power from a mobile station is measured by a base station and the measured level of the desired power is compared with a control target level. If the measured level of the desired power is greater than the control target level, then the base station transmits a control command for reducing the transmission power to the mobile station. Conversely, if the measured level of the desired power is smaller than the control target level, then the base station transmits a control command for increasing the transmission power to the mobile station. The mobile station receives the control command transmitted from the base station, and controls the transmission power based on the received control command.
FIG. 1
of the accompanying drawings illustrates a process of controlling the transmission power of a mobile station based on a control signal from a base station.
As shown in
FIG. 1
, a mobile station
100
a
is positioned more closely to a base station
200
than a mobile station
100
b.
It is general practice to control the transmission power of the mobile station
100
b
so as to be greater than the transmission power of the mobile station
100
a.
Therefore, the mobile station
100
b
positioned more remotely from the base station
200
than the mobile station
100
a
consumes an increased current, causes a greater battery power consumption, and suffers a shorter communication time.
One solution has been to turn off a transmission power amplifier in a mobile station while no communication is made by the mobile station, for thereby preventing a current consumed by the mobile station from being increased.
A conventional portable telephone set which incorporates a scheme for achieving such a solution is illustrated in
FIG. 2
of the accompanying drawings.
As shown in
FIG. 2
, the system comprises an antenna
101
for transmitting and receiving radio waves, a reception RF circuit
103
for spreading a radio signal received by the antenna
101
with a predetermined code, a reception baseband signal processor
104
for decoding the signal spread by the reception RF circuit
103
, a reception voice signal processor
105
for converting the signal decoded by the reception baseband signal processor
104
into an analog signal, a receiver
106
for outputting the analog signal produced by the reception voice signal processor
105
as voice sounds, a transmission power processor
107
for processing a control signal for controlling transmission power which is contained in the signal decoded by the reception baseband signal processor
104
, a microphone
109
for receiving and converting voice sounds into a voice signal, a transmission voice signal processor
110
for converting the voice signal from the microphone
109
into a digital signal, and controlling transmission power based on the control signal processed by the transmission power processor
107
, a transmission baseband signal processor
111
for encoding the digital signal produced by the transmission voice signal processor
110
, a transmission RF circuit
112
for converting the signal encoded by the transmission baseband signal processor
111
into a high-frequency signal, a PA module
113
for amplifying the power of the high-frequency signal produced by the transmission RF circuit
112
according to an amplification factor controlled by the transmission voice signal processor
110
, and a transmission/reception common unit
102
for outputting the radio signal received by the antenna
101
to the reception RF circuit
103
and outputting the signal whose power has been amplified by the PA module
113
to the antenna
101
. The signal whose power has been amplified by the PA module
113
and which has been outputted from the transmission/reception common unit
102
is radiated from the antenna
101
.
The transmission power is amplified on the basis of the control signal processed by the transmission power processor
107
. The control signal processed by the transmission power processor
107
is supplied to the transmission voice signal processor
110
. Only when a voice signal is supplied from the microphone
109
to the transmission voice signal processor
110
, the PA module
113
amplifies the transmission power according to the amplification factor controlled by the transmission voice signal processor
110
.
In the portable telephone set shown in
FIG. 2
, a signal transmitted from a base station (not shown) is received by the antenna
101
, and processed successively by the transmission/reception common unit
102
, the reception RF circuit
103
, the reception baseband signal processor
104
, the reception voice signal processor
105
, and the receiver
106
, which outputs voice sounds. The base station also transmits a control signal for controlling the transmission power of the portable telephone set. The control signal is processed by the transmission power processor
107
, and then supplied to the transmission voice signal processor
110
.
A voice signal supplied from the microphone
109
is processed successively by the transmission voice signal processor
110
, the transmission baseband signal processor
111
, the transmission RF circuit
112
, the PA module
113
, and the transmission/reception common unit
102
, and transmitted from the antenna
101
to the base station. The amplification factor of the PA module
113
is controlled by the transmission voice signal processor
110
based on the control signal processed by the transmission power processor
107
. Only when a voice signal is supplied from the microphone
109
to the transmission voice signal processor
110
, the PA module
113
amplifies the transmission power.
Even if the portable telephone set has a function to be able to turn off the transmission power amplifier when no communication is made by the mobile station, the user of the portable telephone set often fails to recognize such a function. Provided the user recognizes the function, the user tends to communicate via the portable telephone set normally without having any idea as to when and if the transmission power amplifier is turned off. Therefore, there is almost no time in which the transmission power amplifier would be turned off.
When the conventional portable telephone set is positioned remotely from the base station, the portable telephone set consumes a larger current, causes a greater battery power consumption, and suffers a shorter communication time.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a portable telephone set which minimizes an increase in a current consumed thereby and has an increased communication time when the portable telephone set is positioned remotely from a base station, and a communication system which incorporates such a portable telephone set.
According to the present invention, a portable telephone set controls the amplification factor of an amplifier to control the transmission power of the portable telephone set based on a control signal transmitted from the base
To Doris H.
Young & Thompson
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