BASE STATION APPARATUS AND DIRECTIVITY CONTROL METHOD IN MOBILE COMMUNICATION SYSTEM

• US 20100311456A1
• Filed: 07/02/2008
• Published: 12/09/2010
• Est. Priority Date: 07/06/2007
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Cho, Keizo, Inoue, Yuki
• Granted Patent: US 8,588,835 B2
• Time in Patent Office: Days
• US Class Current: 455/513
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic

Abstract

A disclosed base station apparatus for a mobile communication system includes a collection unit collecting measured data from one or more user equipment terminals with respect to each direction of arrival, the measured data including at least quality information of a downlink signal, a conversion unit converting the measured data into an evaluation value in accordance with a predetermined evaluation function, a deriving unit deriving a weight update amount determining directivity based on an angular distribution of the plural evaluation values, and a transmission unit transmitting a downlink signal weighted based on the weight update amount.

Claims

1. A base station apparatus for a mobile communication system, comprising:

a collection unit configured to collect measured data from one or more user equipment terminals with respect to each direction of arrival, the measured data including at least quality information of a downlink signal;

a conversion unit configured to convert the measured data into an evaluation value in accordance with a predetermined evaluation function;

a deriving unit configured to derive a weight update amount based on an angular distribution of the plural evaluation values, the weight update amount determining directivity; and

a transmission unit configured to transmit a downlink signal weighted based on the weight update amount.

2. The base station apparatus according to claim 1, wherein

the predetermined evaluation function increases or decreases depending on a received signal level of the downlink signal.

3. The base station apparatus according to claim 2, wherein

when the received signal level of the downlink signal is in a predetermined range, the evaluation values of the predetermined evaluation function differ depending on whether a ratio of a desired signal power to an undesired signal power is equal to or greater than a predetermined value.

4. The base station apparatus according to claim 3, wherein

when the predetermined evaluation function is represented by f, the following are satisfied:

5. The base station apparatus according to claim 3, wherein

when the predetermined evaluation function is represented by f, the following are satisfied:

6. The base station apparatus according to claim 1, wherein

the angular distribution of the plural evaluation values is derived by classifying the plural evaluation values into the directions of arrival (DOA) and performing a smoothing process on the classified evaluation values.

7. The base station apparatus according to claim 6, wherein

a target data is smoothed based on a locally weighted smoothing process in which a data group within a predetermined range including the target data is weighted averaged.

8. The base station apparatus according to claim 1, wherein

the direction of arrival is derived based on positional information of the user equipment terminal.

9. A directivity control method to be used in a base station apparatus for a mobile communication system, comprising:

a collecting step of collecting measured data from one or more user equipment terminals with respect to each direction of arrival, the measured data including at least quality information of a downlink signal;

a converting step of converting the measured data into an evaluation value in accordance with a predetermined evaluation function;

a deriving step of deriving a weight update amount based on an angular distribution of the plural evaluation values, the weight update amount determining directivity; and

a transmitting step of transmitting a downlink signal weighted based on the weight update amount.

10. The directivity control method according to claim 9, wherein

in the collecting step, the measured data are accumulated in a database so that the number of the measured data is equal to or greater than a predetermined number.