Method of antenna-weight estimation and mobile communication terminal

• US 6,853,839 B2
• Filed: 05/23/2001
• Issued: 02/08/2005
• Est. Priority Date: 05/24/2000
• Status: Expired due to Fees

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Nakamura, Takehiro, Usuda, Masafumi
• Primary Examiner(s): Nguyen, Duc M.
• Application Number:
  US09/863,648
• Publication Number:
  US 20020003833A1
• Time in Patent Office: 1,357 Days
• Field of Search: 455/272, 455/273, 455/275, 455/276.1, 455/277.1, 455/277.2, 455/226.2, 455/226.3, 455/232.1, 455/278.1, 455/63, 455/65, 455/522, 455/127.2, 455132-138, 375/147, 375/148, 375/149, 375/349, 375/346, 370/342, 370/347, 370/252, 370/318, 342/380, 342/383, 342/378
• US Class Current: 455/276.1
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

An antenna weight estimation method in a mobile communication system is capable of improving the accuracy of antenna weight estimation values, thereby improving communication quality and increasing radio channel capacity. It operates instantaneous estimation and accumulative estimation in parallel, in which the former is made for estimating the antenna weight used for received SNIR estimation for transmission power control, and the latter is made for demodulating the received data. Thus, it can obtain the antenna weight for the received SNIR measurement with a minimum delay, and at the same time, it can improve the reliability of the antenna weight for the data demodulation.

Claims

1. A mobile communication terminal in a mobile communication system including the mobile communication terminal and a radio base station carrying out transmission using a plurality of antennas, said mobile communication terminal comprising:

antenna weight instantaneous estimation means for estimating an instantaneous estimation value of an antenna weight from a signal received at a moment of estimation;

antenna weight accumulative estimation means for estimating an accumulative estimation value of the antenna weight from accumulated received signals;

received SNIR calculation means for calculating a received SNIR from the instantaneous estimation value obtained by said antenna weight instantaneous estimation means;

transmission power control command generator for generating a transmission power control command from the received SNIR calculated by said received SNIR calculation means; and

Rake combining means for carrying out Rake combining of the received signals in response to the accumulative estimation value obtained by said antenna weight accumulative estimation means.

2. The mobile communication terminal as claimed in claim 1, wherein said antenna weight instantaneous estimation means comprises:

received signal amplitude estimation means for estimating average received signal amplitude after Rake combining;

noise interference power calculation means for calculating noise interference power after Rake combining;

antenna weight posterior probability calculation means for obtaining posterior probabilities of the antenna weight from the received signal amplitude estimation values obtained by said received signal amplitude estimation means, and from the noise interference power calculation values obtained by said noise interference power calculation means;

antenna weight prior probability calculation means for obtaining prior probabilities of the antenna weight in response to an antenna weight control command transmitted from said mobile communication terminal; and

antenna weight estimation means for estimating the antenna weight from the posterior probabilities obtained by said antenna weight posterior probability calculation means and from the prior probabilities obtained by said antenna weight prior probability calculation means.

3. The mobile communication terminal as claimed in claim 2, wherein said antenna weight accumulative estimation means comprises:

received signal amplitude estimation means for estimating average received signal amplitude after Rake combining;

noise interference power calculation means for calculating noise interference power after Rake combining;

antenna weight posterior probability calculation means for obtaining posterior probabilities of the antenna weight from the received signal amplitude estimation values obtained by said received signal amplitude estimation means, and from the noise interference power calculation values obtained by said noise interference power calculation means;

antenna weight prior probability calculation means for obtaining prior probabilities of the antenna weight in response to an antenna weight control command transmitted from said mobile communication terminal; and

antenna weight estimation means for estimating the antenna weight from the posterior probabilities obtained by said antenna weight posterior probability calculation means and from the prior probabilities obtained by said antenna weight prior probability calculation means.

4. The mobile communication terminal as claimed in claim 3, wherein said received signal amplitude estimation means includes I-component amplitude estimation means and Q-component amplitude estimation means, said I-component amplitude estimation means calculating amplitude of I-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel, and said Q-component amplitude estimation means calculating amplitude of Q-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel;

said noise interference power calculation means includes means for ,calculating noise interference power calculation values from calculation values of noise interference power included in the fingers; and

said antenna weight posterior probability calculation means includes antenna weight I-component posterior probability calculation means and antenna weight Q-component posterior probability calculation means, said antenna weight I-component posterior probability calculation means calculating the posterior probabilities of the antenna weight I-components from the I-component amplitude estimation values obtained by said I-component amplitude estimation means and the noise interference power calculation values obtained by said noise interference power calculation means, and said antenna weight Q-component posterior probability calculation means calculating the posterior probabilities of the antenna weight Q-components from the Q-component amplitude estimation values obtained by said Q-component amplitude estimation means and the noise interference power calculation values obtained by said noise interference power calculation means.

5. The mobile communication terminal as claimed in claim 2, wherein said received signal amplitude estimation means includes I-component amplitude estimation means and Q-component amplitude estimation means, said I-component amplitude estimation means calculating amplitude of I-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel, and said Q-component amplitude estimation means calculating amplitude of Q-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel;

said noise interference power calculation means includes means for calculating noise interference power calculation values from calculation values of noise interference power included in the fingers; and

said antenna weight posterior probability calculation means includes antenna weight I-component posterior probability calculation means and antenna weight Q-component posterior probability calculation means, said antenna weight I-component posterior probability calculation means calculating the posterior probabilities of the antenna weight I-components from the I-component amplitude estimation values obtained by said I-component amplitude estimation means and the noise interference power calculation values obtained by said noise interference power calculation means, and said antenna weight Q-component posterior probability calculation means calculating the posterior probabilities of the antenna weight Q-components from the Q-component amplitude estimation values obtained by said Q-component amplitude estimation means and the noise interference power calculation values obtained by said noise interference power calculation means.

6. The mobile communication terminal as claimed in claim 1, wherein said antenna weight accumulative estimation means comprises:

received signal amplitude estimation means for estimating average received signal amplitude after Rake combining;

noise interference power calculation means for calculating noise interference power after Rake combining;

antenna weight posterior probability calculation means for obtaining posterior probabilities of the antenna weight from the received signal amplitude estimation values obtained by said received signal amplitude estimation means, and from the noise interference power calculation values obtained by said noise interference power calculation means;

antenna weight prior probability calculation means for obtaining prior probabilities of the antenna weight in response to an antenna weight control command transmitted from said mobile communication terminal; and

antenna weight estimation means for estimating the antenna weight from the posterior probabilities obtained by said antenna weight posterior probability calculation means and from the prior probabilities obtained by said antenna weight prior probability calculation means.

7. The mobile communication terminal as claimed in claim 6, wherein said received signal amplitude estimation means includes I-component amplitude estimation means and Q-component amplitude estimation means, said I-component amplitude estimation means calculating amplitude of I-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel, and said Q-component amplitude estimation means calculating amplitude of Q-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel;

said noise interference power calculation means includes means for calculating noise interference power calculation values from calculation values of noise interference power included in the fingers; and

said antenna weight posterior probability calculation means includes antenna weight I-component posterior probability calculation means and antenna weight Q-component posterior probability calculation means, said antenna weight I-component posterior probability calculation means calculating the posterior probabilities of the antenna weight I-components from the I-component amplitude estimation values obtained by said I-component amplitude estimation means and the noise interference power calculation values obtained by said noise interference power calculation means, and said antenna weight Q-component posterior probability calculation means calculating the posterior probabilities of the antenna weight Q-components from the Q-component amplitude estimation values obtained by said Q-component amplitude estimation means and the noise interference power calculation values obtained by said noise interference power calculation means.

8. A mobile communication terminal in a mobile communication system including the mobile communication terminal and a radio base station carrying out transmission using a plurality of antennas, said mobile communication terminal comprising:

received signal amplitude estimation means for estimating average received signal amplitude after Rake combining;

noise interference power calculation means for calculating noise interference power after Rake combining;

antenna weight posterior probability calculation means for obtaining posterior probabilities of the antenna weight from the received signal amplitude estimation value obtained by said received signal amplitude estimation means, and from the noise interference power calculation value obtained by said noise interference power calculation means;

antenna weight prior probability calculation means for obtaining prior probabilities of the antenna weight in response to an antenna weight control command transmitted from said mobile communication terminal; and

antenna weight estimation means for estimating the antenna weight from the posterior probabilities obtained by said antenna weight posterior probability calculation means and from the prior probabilities obtained by said antenna weight prior probability calculation means.

9. The mobile communication terminal as claimed in claim 8, wherein said received signal amplitude estimation means includes I-component amplitude estimation means and Q-component amplitude estimation means, said I-component amplitude estimation means calculating amplitude of I-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel, and said Q-component amplitude estimation means calculating amplitude of Q-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel;

said noise interference power calculation means includes means for calculating noise interference power calculation values from calculation values of noise interference power included in the fingers; and

said antenna weight posterior probability calculation means includes antenna weight I-component posterior probability calculation means and antenna weight Q-component posterior probability calculation means, said antenna weight I-component posterior probability calculation means calculating the posterior probabilities of the antenna weight I-components from the I-component amplitude estimation values obtained by said I-component amplitude estimation means and the noise interference power calculation values obtained by said noise interference power calculation means, and said antenna weight Q-component posterior probability calculation means calculating the posterior probabilities of the antenna weight Q-components from the Q-component amplitude estimation values obtained by said Q-component amplitude estimation means and the noise interference power calculation values obtained by said noise interference power calculation means.

10. An antenna weight estimation method in a mobile communication system including a mobile communication terminal and a radio base station carrying out transmission using a plurality of antennas, said antenna weight estimation method comprising:

an antenna weight instantaneous estimation step of estimating an instantaneous estimation value of an antenna weight from a signal received at a moment of estimation;

an antenna weight accumulative estimation step of estimating an accumulative estimation value of the antenna weight from accumulated received signals;

a received SNIR calculation step of calculating a received SNIR from the instantaneous estimation value obtained by said antenna weight instantaneous estimation step;

a transmission power control command generating step of generating a transmission power control command from the received SNIR calculated by said received SNIR calculation step; and

a Rake combining step of carrying out Rake combining of the received signals in response to the accumulative estimation value obtained by said antenna weight accumulative estimation step.

11. The antenna weight estimation method as claimed in claim 10, wherein said antenna weight instantaneous estimation step comprises:

a received signal amplitude estimation step of estimating average received signal amplitude after Rake combining;

a noise interference power calculation step of calculating noise interference power after Rake combining;

an antenna weight posterior probability calculation step of obtaining posterior probabilities of the antenna weight from the received signal amplitude estimation values obtained by said received signal amplitude estimation step, and from the noise interference power calculation values obtained by said noise interference power calculation step;

an antenna weight prior probability calculation step of obtaining prior probabilities of the antenna weight in response to an antenna weight control command transmitted from said mobile communication terminal; and

an antenna weight estimation step of estimating the antenna weight from the posterior probabilities obtained by said antenna weight posterior probability calculation step and from the prior probabilities obtained by said antenna weight prior probability calculation step.

12. The antenna weight estimation method as claimed in claim 10, wherein said antenna weight accumulative estimation step comprises:

a received signal amplitude estimation step of estimating average received signal amplitude after Rake combining;

a noise interference power calculation step of calculating noise interference power after Rake combining;

an antenna weight posterior probability calculation step of obtaining posterior probabilities of the antenna weight from the received signal amplitude estimation values obtained by said received signal amplitude estimation step, and from the noise interference power calculation values obtained by said noise interference power calculation step;

an antenna weight prior probability calculation step of obtaining prior probabilities of the antenna weight in response to an antenna weight control command transmitted from said mobile communication terminal; and

an antenna weight estimation step of estimating the antenna weight from the posterior probabilities obtained by said antenna weight posterior probability calculation step and from the prior probabilities obtained by said antenna weight prior probability calculation step.

13. The antenna weight estimation method as claimed in claim 12, wherein said received signal amplitude estimation step includes an I-component amplitude estimation step and a Q-component amplitude estimation step, said I-component amplitude estimation step calculating amplitude of I-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel, and said Q-component amplitude estimation step calculating amplitude of Q-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel;

said noise interference power calculation step includes a step of calculating noise interference power calculation values from calculation values of noise interference power included in the fingers; and

said antenna weight posterior probability calculation step includes an antenna weight I-component posterior probability calculation step and an antenna weight Q-component posterior probability calculation step, said antenna weight I-component posterior probability calculation step calculating the posterior probabilities of the antenna weight I-components from the I-component amplitude estimation values obtained by said I-component amplitude estimation step and the noise interference power calculation values obtained by said noise interference power calculation step, and said antenna weight Q-component posterior probability calculation step calculating the posterior probabilities of the antenna weight Q-components from the Q-component amplitude estimation values obtained by said Q-component amplitude estimation step and the noise interference power calculation values obtained by said noise interference power calculation step.

14. The antenna weight estimation method as claimed in claim 11, wherein said antenna weight accumulative estimation step comprises:

a received signal amplitude estimation step of estimating average received signal amplitude after Rake combining;

a noise interference power calculation step of calculating noise interference power after Rake combining;

an antenna weight posterior probability calculation step of obtaining posterior probabilities of the antenna weight from the received signal amplitude estimation values obtained by said received signal amplitude estimation step, and from the noise interference power calculation values obtained by said noise interference power calculation step;

an antenna weight prior probability calculation step of obtaining prior probabilities of the antenna weight in response to an antenna weight control command transmitted from said mobile communication terminal; and

an antenna weight estimation step of estimating the antenna weight from the posterior probabilities obtained by said antenna weight posterior probability calculation step and from the prior probabilities obtained by said antenna weight prior probability calculation step.

15. The antenna weight estimation method as claimed in claim 14, wherein said received signal amplitude estimation step includes an I-component amplitude estimation step and a Q-component amplitude estimation step, said I-component amplitude estimation step calculating amplitude of I-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel, and said Q-component amplitude estimation step calculating amplitude of Q-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel;

said noise interference power calculation step includes a step of calculating noise interference power calculation values from calculation values of noise interference power included in the fingers; and

said antenna weight posterior probability calculation step includes an antenna weight I-component posterior probability calculation step and an antenna weight Q-component posterior probability calculation step, said antenna weight I-component posterior probability calculation step calculating the posterior probabilities of the antenna weight I-components from the I-component amplitude estimation values obtained by said I-component amplitude estimation step and the noise interference power calculation values obtained by said noise interference power calculation step, and said antenna weight Q-component posterior probability calculation step calculating the posterior probabilities of the antenna weight Q-components from the Q-component amplitude estimation values obtained by said Q-component amplitude estimation step and the noise interference power calculation values obtained by said noise interference power calculation step.

16. The antenna weight estimation method as claimed in claim 11, wherein said received signal amplitude estimation step includes an I-component amplitude estimation step and a Q-component amplitude estimation step, said I-component amplitude estimation step calculating amplitude of I-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel, and said Q-component amplitude estimation step calculating amplitude of Q-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel;

said noise interference power calculation step includes a step of calculating noise interference power calculation values from calculation values of noise interference power included in the fingers; and

said antenna weight posterior probability calculation step includes an antenna weight I-component posterior probability calculation step and an antenna weight Q-component posterior probability calculation step, said antenna weight I-component posterior probability calculation step calculating the posterior probabilities of the antenna weight I-components from the I-component amplitude estimation values obtained by said I-component amplitude estimation step and the noise interference power calculation values obtained by said noise interference power calculation step, and said antenna weight Q-component posterior probability calculation step calculating the posterior probabilities of the antenna weight Q-components from the Q-component amplitude estimation values obtained by said Q-component amplitude estimation step and the noise interference power calculation values obtained by said noise interference power calculation step.

17. An antenna weight estimation method in a mobile communication system including a mobile communication terminal and a radio base station carrying out transmission using a plurality of antennas, said antenna weight estimation method comprising:

a received signal amplitude estimation step of estimating average received signal amplitude after Rake combining;

a noise interference power calculation step of calculating noise interference power after Rake combining;

an antenna weight posterior probability calculation step of obtaining posterior probabilities of the antenna weight from the received signal amplitude estimation value obtained by said received signal amplitude estimation step, and from the noise interference power calculation value obtained by said noise interference power calculation step;

an antenna weight prior probability calculation step of obtaining prior probabilities of the antenna weight in response to an antenna weight control command transmitted from said mobile communication terminal; and

an antenna weight estimation step of estimating the antenna weight from the posterior probabilities obtained by said antenna weight posterior probability calculation step and from the prior probabilities obtained by said antenna weight prior probability calculation step.

18. The antenna weight estimation method as claimed in claim 17, wherein said received signal amplitude estimation step includes an I-component amplitude estimation step and a Q-component amplitude estimation step, said I-component amplitude estimation step calculating amplitude of I-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel, and said Q-component amplitude estimation step calculating amplitude of Q-components of the received signals from channel estimation values including the antenna weight obtained from individual pilot channels received at individual fingers and channel estimation values obtained from a common pilot channel;

said noise interference power calculation step includes a step of calculating noise interference power calculation values from calculation values of noise interference power included in the fingers; and

said antenna weight posterior probability calculation step includes an antenna weight I-component posterior probability calculation step and an antenna weight Q-component posterior probability calculation step, said antenna weight I-component posterior probability calculation step calculating the posterior probabilities of the antenna weight I-components from the I-component amplitude estimation values obtained by said I-component amplitude estimation step and the noise interference power calculation values obtained by said noise interference power calculation step, and said antenna weight Q-component posterior probability calculation step calculating the posterior probabilities of the antenna weight Q-components from the Q-component amplitude estimation values obtained by said Q-component amplitude estimation step and the noise interference power calculation values obtained by said noise interference power calculation step.