a system model applied to the present invention will first be described a burst transmission frame of a radio communication system has bursts including two data transport parts also known as sub frames each comprised of n data symbols mid ambles which are training sequences predefined between a transmitter and a receiver having l m chips are included in each data carrying part so that channel characteristics and interferences in a radio section can be measured the radio communication system supports multiple access based on transmit diversity code division multiple access td cdma and spreads each data symbol using a q chip orthogonal variable spreading factor ovsf code which is a user specific cdma code in a radio environment there are k users per cell and frequency band and per time slot as a whole there are k i inter cell interferences a base station or a node b uses an array antenna having k a antenna elements assuming that a signal transmitted by a k th user k 1 k is incident upon impinges on the array antenna in k d d different directions each of the directions is represented by a cardinal identifier k d k d 1 k d d then a phase factor of a k d th spatial signal which is incident upon the array antenna from a k th user i e a user k through a k a th antenna element i e an antenna element k a k a 1 k a is defined as u03c8 u2061 k k a k d 2 u2062 u03c0 u2062 u2062 l k a u03bb u00b7 cos u2061 u03b2 k k d u03b1 k a 1 in equation 1 u03b1 k a denotes an angle between a virtual line connecting antenna elements arranged in a predetermined.