Transmission power amplifier unit

Abstract

A transmission power amplifier unit of a base-station apparatus for compensating for non-linear distortion of a transmission power amplifier by feed-forward control is provided with a gain varying unit for varying gain of the transmission power amplifier unit. At start-up of the transmission power amplifier unit, a controller determines whether the base-station apparatus is in a blossoming mode or breathing mode, maximizes gain of the transmission power amplifier unit by controlling the gain varying unit if the mode is the blossoming mode and increases the gain gradually in proportion to the passage of time if the mode is the breathing mode.

Description

BACKGROUND OF THE INVENTION [0001] This invention relates to a transmission power amplifier unit and, more particularly, to a transmission power amplifier unit, which has a transmission power amplifier, for compensating for non-linear distortion of the transmission power amplifier by feed-forward control. [0002] Frequency resources have become tight in recent years and in wireless communications there is growing use of high-efficiency transmission using digital techniques. In instances where multilevel amplitude modulation is applied to wireless communications, a vital technique is one which can suppress non-linear distortion by linearizing the amplitude characteristic of the power amplifier on the transmitting side and reduce the leakage of power between adjacent channels. Also essential is a technique which compensates for the occurrence of distortion that arises when an attempt is made to improve power efficiency by using an amplifier that exhibits poor linearity. [0003]FIG. 12 i...

AI Technical Summary

Benefits of technology

[0023] Accordingly, an object of the present invention increase the transmission power of a high-power amplifier linearly with time when a station is established.

[0024] Another object of the present invention is to so arrange it that when power is introduced to a high-power amplifier (i.e., when the amplifier is started up), an excessive current will not enter a sub-amp and cause destruction of the sub-amp, and to so arrange it that non-linear distortion of a main amp can be compensated for quickly.

[0025] A transmission power amplifier unit of a base-station apparatus for compensating for non-linear distortion of a transmission power amplifier by feed-forward control is provided with (1) a gain varying unit for varying gain of the transmission power amplifier unit, and (2) a controller for controlling the gain varying unit. At start-up of (introduction of power to) the transmission power amplifier unit, the controller determines whether the base-station apparatus is in a blossoming mode or breathing mode, maximizes gain of the transmission power amplifier unit if the mode is the blossoming mode and increases the gain of the transmission power amplifier unit gradually if the mode is the breathing mode.

[0027] If the above arrangement is adopted, the transmission power amplifier unit holds the gain constant at establishment of a station because the base station will be in the blossoming mode. When a station is established, therefore, output power (transmission power) of the transmission power amplifier unit can be increased linearly with time. Further, when power is introduced to a transmission power amplifier unit replaced for the sake of testing or maintenance, the base station is in the breathing mode and, hence, the transmission power amplifier unit gradually raises gain. As a result, it can be so arranged that a sub-amp will not be destroyed owing to input of excessive power. Moreover, non-linear distortion of a main amp can compensated for quickly.

Problems solved by technology

In other words, if a large amount of power is suddenly output to enlarge a cell when a station is established, calls from a large number of terminals concentrate at one time, call processing cannot keep pace and a variety of problems arise.

Otherwise reception will not be possible even if transmission is or transmission will not be possible even if reception is.

Further, in feed-forward control, a comparatively long period of time is required to settle in the steady state if a large signal is suddenly applied.

If the transmission power SOUT of the base station ceases varying linearly with respect to time, then it is no longer possible to exercise the original control that attempts to enlarge the cell (the transmit area) gradually in proportion to time.

A particular problem is that since the base station that establishes the link is changed over owing to the reception power of the mobile terminal, the base station that establishes the link will be changed over frequently unless transmission power control of the base station is performed smoothly when a station is set up.

A further problem is that a difference develops between the transmittable area and receivable area so that, depending upon the region, transmission is possible but reception is not, or vice versa.

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