Radio base station and method of controlling radio communications

• US 20030043770A1
• Filed: 09/06/2002
• Published: 03/06/2003
• Est. Priority Date: 09/06/2001
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Futakata, Toshiyuki, Moon, Sung Uk
• Granted Patent: US 7,502,359 B2
• Time in Patent Office: Days
• US Class Current: 370/337
• CPC Class Codes: H04B 7/005 Control of transmission; Equalising
• CPC Class Codes: H04B 7/0667 of delayed versions of same signal using space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0678 using different spreading codes between antennas code allocation H04J13/16

Abstract

The present invention provides a radio base station for preventing degradation of transmission quality characteristics even when there are time differences between the instant of channel estimation of uplink time slots UL#1 to UL#N and the instant of transmission of transmission data via downlink time slots DL#1 to DL#N. The radio base station includes transmit diversity controllers 14₁ to 14_N for controlling transmit diversity to be used for downlink time slots DL#1 to DL#N and a data transmitter 15 for transmitting data via downlink time slots DL#1 to DL#N using the controlled transmit diversity.

Claims

1. A radio base station comprising:

a channel estimator configured to perform channel estimation of an uplink time slot;

a transmit diversity controller configured to control transmit diversity to be used for each downlink time slot, based on said channel estimation and the time difference from the instant of said channel estimation; and

a data transmitter configured to transmit data in said downlink time slot using said controlled transmit diversity.

2. A radio base station as set forth in claim 1, wherein:

said transmit diversity controller determines whether or not to use transmit diversity for each downlink time slot, based on said channel estimation and the time difference from the instant of said channel estimation.

3. A radio base station as set forth in claim 1, wherein:

said transmit diversity controller determines a kind of transmit diversity to be used for each downlink time slot, based on said channel estimation and the time difference from the instant of said channel estimation.

4. A method of controlling radio communications, comprising the steps of:

a) performing, at a radio base station, channel estimation of an uplink time slot;

b) controlling, at said radio base station, transmit diversity to be used for each downlink time slot, based on said channel estimation and the time difference from the instant of said channel estimation; and

c) transmitting, at said radio base station, data in said downlink time slot using said controlled transmit diversity.

5. A method of controlling radio communications as set forth in claim 4, wherein:

in said step b), it is determined whether or not to use transmit diversity for each downlink time slot, based on said channel estimation and the time difference from the instant of said channel estimation.

6. A method of controlling radio communications as set forth in claim 4, wherein:

in said step b), a kind of transmit diversity to be used is determined for each downlink time slot, based on said channel estimation and the time difference from the instant of said channel estimation.