Nippon Telegraph and Telephone Corporation

Teruya Fujii

Toshio Suzuki

Toshio Nojima

Masayuki Sakamoto

Sadayuki Nishiki

Hisao Takahashi

Hitoshi Odate

A re-use partition of cells in a mobile communication system has an outer cell (30) and an inner cell (20) which is provided in the outer cell (30). An interval of cells using the same channel or the same frequency in the inner cells is shorter than an interval in the outer cells, which is the nature of a re-use partition. Communication between a base station and a mobile station is carried out by using a channel having a higher received level of an outer cell channel or an inner cell channel. A base station has a first beam tilt antenna having tilt angle (.THETA..sub.out) for an outer cell (30), and a second beam tilt antenna having tilt angle (.THETA..sub.in) so that .THETA..sub.in is larger than .THETA..sub.out. A speech channel and a control channel are provided for each of the first antenna and the second antenna.

Structure of cells within a mobile communication system

The system for measuring the spillover signal from a transmitter to a receiver in a same frequency repeater or a booster has a frequency conversion device which slightly offsets the transmission frequency from the reception frequency, and a signal detector which measures the offset frequency component in the reception signal. The offset frequency is around 100 Hz, which is higher than the fading frequency, and low enough not to affect the operation of receivers. The measured spillover level is used to control the gain of the repeater, and/or to cancel the spillover signal, so that the repeater has the maximum gain without suffering from oscillation.

Repeater for a same frequency with spillover measurement

Growing community of inventors

Kanagawa, Japan

Teruya Fujii