Telecommunications – Transmitter – Power control – power supply – or bias voltage supply
Reexamination Certificate
1999-12-20
2004-01-06
Appiah, Charles (Department: 2682)
Telecommunications
Transmitter
Power control, power supply, or bias voltage supply
C455S241100, C455S522000, C330S133000
Reexamination Certificate
active
06675000
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is related to a radio communication apparatus such as a mobile communication appliance for performing a mobile communication in a portable telephone, and also related to a transmission power control method in this radio communication apparatus.
In general, mobile communication appliances such as portable telephone units are equipped with functions capable of controlling transmission power of own units based upon distances between base stations and mobile stations while information is transmitted. In the multiple access type communication system for multiplexing a plurality of communication channels, a transmission power control for maintaining power of a signal reached to a base station at a constant value is necessarily required in order to increase a frequency utilization efficiency while reducing interference occurred between communication channels.
More specifically, in a CDMA (Code Division Multiple Access) type mobile communication appliance with employing a spread spectrum communication technique, since a single frequency band is commonly used by a plurality of users, there are great possibilities that a signal having low transmission power is masked by a signal having high transmission power, namely a so-called “far
ear problem”. Thus, the following problem would occur. That is, a signal transmitted from another station may function as an interference signal wave to cause a line quality to be deteriorated. To solve such a problem, conventionally, various sorts of transmission power control techniques have been studied. In particular, the transmission power control system by the closed loop is known as the transmission power control system capable of tracing such interference signals which are instantaneously varied. More specifically, in the CDMA system, the transmission power control with a high linearity and a wide dynamic range (for instance, 70 to 80 dB) is required. Furthermore, in the wide-band CDMA (W-CDMA), higher precision of the transmission power is required when signals having high power are transmitted, and thus, higher precision of the transmission power control operation is further required. This wide-band CDMA system has been considered as the mobile communication system for the next generation.
FIG. 19
is a flow chart for showing an example of the conventional transmission power control method by the closed loop. This transmission power control method may be used in the transmission power control and other controls by open/close loop controls executed based upon the IS-95 rule of TIA (Telecommunications Industry Association).
In a communication is established between a base station and a mobile station, the mobile station determines a transmission power control bit based on reception power of a reception signal wave (desirable signal wave) sent from the base station (S
101
), inserts this transmission power control bit into a transmission signal, and then transmits the resultant transmission signal to the base station. The base station receives the signal transmitted from the mobile station, extracts the transmission power control bit from the reception signal (S
105
), and then controls a variable power amplifier of the own station in accordance with the instruction of this transmission power control bit (S
106
).
Similarly, the base station determines a transmission power control bit based on reception power of a reception signal wave sent from the mobile station (S
104
), inserts this transmission power control bit into a transmission signal, and then transmits the resultant transmission signal to the mobile station. The mobile station receives the signal transmitted from the base station, extracts the transmission power control bit from the reception signal (S
102
), and then controls a variable power amplifier of the own station in accordance with the instruction of this transmission power control bit (S
103
).
Since such a transmission power control is carried out, it is possible to keep the reception power substantially constant in both the base station and the mobile station irrespective of the distance between the base station and the mobile station.
For example, in “TRANSMISSION POWER CONTROL METHOD AND SPREAD SPECTRUM COMMUNICATION APPARATUS WITH USING CONTROL METHOD THEREOF” described in Japanese Laid-open Patent Application No. Hei-8-32513 opened in 1996, the transmission power is controlled based upon the transmission power control amount corresponding to a total number of the transmission power bit having the same bit value which is continuously received. As a consequence, the increased or decreased step of the transmission power are increased while the continuous reception time has elapsed in order to follow the rapid variation in the communication path.
In the above-explained conventional transmission power control method, since the transmission power control operation is carried out by a single transmission power control system (variable power amplifier), the high-precision variable power amplifier is required in order that, in particular, such a transmission power control operation having a high linearity and a wide dynamic range is carried out. This transmission power control operation is required for the CDMA system Also, the variable power amplifier amplification function must be carried out in high precision.
However, when a variable power amplifier is controlled in high precision with employment of such a high-precision variable power amplifier, the following problems will occur. That is, a circuit scale is increased, a power consumption amount is increased, and an entire apparatus would be made in high cost. Also, it is practically difficult to employ only one variable power amplifier for realizing a wide-range gain control, while maintaining high precision. Furthermore, in the case that a mobile station is a portable telephone, while the transmission power is controlled in high precision, the power consumption is required to be suppressed by reducing the circuit scale (namely, circuit is made simple and compact). As a result, considering the power consumption, the portability, and the apparatus cost, there are various difficulties in order to realize the high-precision transmission power control over the wide range by using the conventional transmission power control method.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above-described problems, and therefore, has an object to provide a compact radio communication apparatus operable under low power consumption, and a transmission power control method in such a radio communication apparatus, while realizing a transmission power control means with having a simple arrangement and operable under low power consumption, and increasing precision of a transmission power control operation.
To achieve the above-described object, a radio communication apparatus, according to the present invention, comprises a transmission power control function capable of controlling transmission power to a communication counter station, comprising: a plurality of variable power amplifying means for amplifying transmission power; and variable: power amplifying-controlling means for controlling the plurality of variable power amplifying means in either a serial control manner or a parallel control manner over an entire control range to thereby perform a variable amplifying-controlling operation.
Preferably, the variable power amplifying-controlling means compares own transmission power stored therein with a predetermined threshold value, and then, performs the serial control manner with respect to the plurality of variable power amplifying means over the entire control range based upon the comparison result.
Preferably, the variable power amplifying-controlling means includes: control bit extracting means for extracting a transmission power control bit transmitted from a communication counter station; transmission power storing means for updating the own transmission power stored thereinto based upon the transmission power co
Appiah Charles
Matsushita Electric - Industrial Co., Ltd.
Pearne & Gordon LLP
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