Antennas, Base and Mobile Stations -5.Basic Configuration of Base Station Amplifier
The base station amplifiers consist of a transmission power amplifier installed indoors and a low-noise reception amplifier installed outdoors near the antenna. The transmission power amplifier amplifies the radio signals modulated by the modems to the desired transmission level. Two amplification methods can be used: individual amplification and common amplification.
In individual amplification, each radio signal amplified by individual amplifiers must then be power-synthesized by channel synthesizer. In common amplification, after each radio signal is power-synthesized at the input side of the amplifier, they are collectively synthesized by a single linear amplifier.
One technological issue in common amplification is how to suppress the occurrence of intermodulation distortion. To overcome this problem, NTT DOCOMO has developed a revolutionary distortion compensation technology called self-adjustment feed forward, or SAFF, which has been successful in almost completely suppressing distortion.
Basic Configuration of Common Transmission Power Amplifier