Hitachi, Ltd.

Hitachi Communication Technologies, Ltd.

Toshiaki Kurokawa

Kazuyuki Hori

Kazuhito Ishida

Shouhei Murakami

Tsutomu Yamaguchi

Shiro Mazawa

Masamitsu Nishikido

Yuji Ishida

Keiichi Hirota

Norie Hara

Seiko Shimogawa

Seiko Shimogama

In a time-interleaved AD converter which combines together low-speed high-resolution AD converters for effective high speed operation, various deterioration factors possessed by each of the converters, including DC offset, conversion gain error, sampling timing error, and a frequency characteristic, need to be compensated. The compensation is performed through nonlinear filter operation in which a constant term is added to linear filter operation. A high-speed low-resolution AD converter is separately used, and through adaptive signal processing in which an output signal thereof is defined as an instruction signal, a compensation coefficient is calculated. In this condition, the compensation can be performed without the influence of quantization noise attributable to the high-speed low-resolution AD converter.

Time-interleaved AD converter

Unlike a prior art digital predistortion compensation device for determining a compensation coefficient based on absolute value information about a baseband complex input signal, the present invention performs distortion compensation calculation in accordance with a complex coefficient polynomial using real and imaginary parts of the baseband complex input signal as its variables.

Predistortion amplifier

A base station controller and a mobile station to achieve high speed transmission and effective use of radio resources in a radio communications system. A communication system includes a plurality of base stations in order to provide communication among a mobile station, another mobile station and a communication link. The communication links for use in the communication are selected base on the channel quality of the communications links. The communication information is then demultiplexed for each selected link, and the data is sent parallel by way of the demultiplexed communication information along the selected communication links to allow high speed transmission.

Base station controller and mobile station

Even if traffic concentrates on a specific place in a cellular radio communication in which a base station communicates with its corresponding wireless terminal, power to be used up or consumed by the base station can be restricted. Further, the equality of communication is satisfactory and the need for a change in the conventional wireless terminal is eliminated. Therefore, two types of sectors corresponding to a wide range sector and narrow range sectors each overlapping with the wide range sector are defined in a multi-sector model. Further, a wide range antenna for the wide range sector and narrow range antennas for the narrow range sectors are separately prepared for the base station. Afterwards, signals are transmitted to wireless terminals located within the narrow range sectors by using both the wide range antenna and the narrow range antennas. In the case of CDMA in particular, the same signal is transmitted with respect to a traffic channel alone.

Radio communication method and radio communication system

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Yokohama, Japan

Toshiaki Kurokawa