Communication terminal device and channel estimating method

A communication terminal apparatus that performs radio communication with a base station apparatus that transmits from a first antenna and a second antenna common pilot channel signals that are separable, the common pilot channel signal transmitted from the first antenna being accompanied by a dedicated channel signal having a same phase as said common pilot channel signal, the common pilot channel signal transmitted from the second antenna being accompanied by a dedicated channel having an amplitude multiplied by a amplitude coefficient selected from a plurality of candidate amplitude coefficients and having a phase rotated from said common pilot channel signal by a phase rotation amount selected from a plurality of candidate phase rotation amounts, the communication terminal apparatus comprising:

• a first channel estimator that performs channel estimation with respect to the common pilot channel signal from the first antenna and outputs a first estimation value;
• a second channel estimator that performs channel estimation with respect to the common pilot channel signal from the second antenna and outputs a second estimation value;
• a third channel estimator that performs channel estimation with respect to the dedicated channel signals from the first and second antennas and outputs a third estimation value;
• an amplitude and phase rotation amount estimator that estimates the amplitude coefficient and the phase rotation amount selected in the base station apparatus;
• a channel estimation value synthesizer that synthesizes the first estimation value, a value obtained from the second estimation value by applying the amplitude coefficient and the phase rotation amount estimated in the amplitude and phase rotation amount estimator to said second estimation value, and the third estimation value so as to calculate a definite channel estimation value;
• and
• a demodulator that demodulates the dedicated channel signals using the channel estimation value calculated in the channel estimation value synthesizer.

A channel estimation method in a communication terminal apparatus that performs radio communication with a base station apparatus that transmits from a first antenna and a second antenna common pilot channel signals that are separable, the common pilot channel signal transmitted from the first antenna being accompanied by a dedicated channel signal having a same phase as said common pilot channel signal, the common pilot channel signal transmitted from the second antenna being accompanied by a dedicated channel having a phase rotated from said common pilot channel signal by a candidate phase rotation amount selected from a plurality of candidate phase rotation amounts, the communication terminal apparatus comprising:

• a first channel estimation step of performing channel estimation with respect to the common pilot channel signal from the first antenna and outputting a first estimation value;
• a second channel estimation step of performing channel estimation with respect to the common pilot channel signal from the second antenna and outputting a second estimation value;
• a third channel estimation step of performing channel estimation with respect to the dedicated channel signals from the first and second antennas and outputting a third estimation value;
• a phase rotation amount estimation step of estimating the phase rotation amount selected in the base station apparatus;
• and
• a channel estimation value synthesis step of synthesizing the first estimation value, a value obtained from the second estimation value by applying the phase rotation amount estimated in the phase rotation amount estimation step to said second estimation value, and the third estimation value so as to calculate a definite channel estimation value.

A channel estimation method in a communication terminal apparatus that performs radio communication with a base station apparatus that transmits from a first antenna and a second antenna common pilot channel signals that are separable, the common pilot channel signal transmitted from the first antenna being accompanied by a dedicated channel signal having a same phase as said common pilot channel signal, the common pilot channel signal transmitted from the second antenna being accompanied by a dedicated channel having an amplitude multiplied by an amplitude coefficient selected from a plurality of candidate amplitude coefficients and having a phase rotated from said common pilot channel signal by a phase rotation amount selected from a plurality of candidate phase rotation amounts, the communication terminal apparatus comprising:

• a first channel estimation step of performing channel estimation with respect to the common pilot channel signal from the first antenna and outputting a first estimation value;
• a second channel estimation step of performing channel estimation with respect to the common pilot channel signal from the second antenna and outputting a second estimation value;
• a third channel estimation step of performing channel estimation with respect to the dedicated channel signals from the first and second antennas and outputting a third estimation value;
• an amplitude and phase rotation amount estimation step of estimating the amplitude coefficient and the phase rotation amount selected in the base station apparatus;
• and
• a channel estimation value synthesis step of synthesizing the first estimation value, a value obtained from the second estimation value by applying the amplitude coefficient and the phase rotation amount estimated in the amplitude and phase rotation amount estimator to said second estimation value, and the third estimation value so as to calculate a definite channel estimation value.