Wireless communication system, radio base station apparatus and radio terminal apparatus

Abstract

A wireless communication system comprises radio base station apparatuses each of which transmits an estimation pilot in advance for estimating the quality of a downlink communication after a spatial signal processing performed after a time unified among the radio base station apparatuses; and radio terminal apparatuses each of which receives the estimation pilot to determine the quality of the downlink communication, thereby reporting the determined downlink communication quality to the radio base station apparatus via an uplink channel. The estimation pilot is transmitted at the same time and frequency established among the radio base station apparatuses by use of the same directivity beam as used for transmitting the data after the unified time.

What is claimed is: 
     
         1 . A wireless communication method executed by a base station, including steps of:
 generating, by the base station, estimation pilot signals for estimating downlink communication qualities after an elapse of a predetermined time;   transmitting, by the base station, the generated estimation pilot signals in advance of transmitting data after an elapse of a predetermined time;   generating, by the base station, detection pilot signals that a mobile station uses for processing the transmission data; and   transmitting, by the base station, the generated detection pilot signals,   wherein a directional gain of the estimation pilot signals is the same as that of the detection pilot signals.   
     
     
         2 . The wireless communication method according to  claim 1 , further including a step of transmitting, by the base station, the generated estimation pilot signals and the generated detection pilot signals after multiplexing said signals. 
     
     
         3 . The wireless communication method according to  claim 1  wherein the estimation pilot signals are transmitted for a time period which is longer than a time period of the detection pilot signals. 
     
     
         4 . A wireless communication system, comprising:
 at least one mobile station; and   at least one base station which receives downlink communication quality information sent from the at least one mobile station, and transmits data to the at least one of mobile station based on the received downlink communication quality information,   wherein the at least one base station:   generates estimation pilot signals for estimating downlink communication qualities after an elapse of a predetermined time;   transmits the generated estimation pilot signals in advance of transmitting data after an elapse of a predetermined time;   generates detection pilot signals that the at least one of the mobile stations uses for processing the transmission data; and   transmits the generated detection pilot signals,   wherein a directional gain of the estimation pilot signals is the same as that of the detection pilot signals.   
     
     
         5 . The wireless communication system according to  claim 4 , wherein the base station transmits the generated estimation pilot signals and the generated detection pilot signals after multiplexing said signals. 
     
     
         6 . The wireless communication system according to  claim 4 , wherein the estimation pilot signals are transmitted for a time period which is longer than a time period of the detection pilot signals. 
     
     
         7 . A base station provided in a wireless communication system which receives downlink communication quality information sent from a mobile station, and transmits data to the mobile station based on the received downlink communication quality information,
 wherein the base station:   generates estimation pilot signals for estimating downlink communication qualities after an elapse of a predetermined time;   transmits the generated estimation pilot signals in advance of transmitting data after an elapse of a predetermined time;   generates detection pilot signals that the mobile station uses for processing the transmission data; and   transmits the generated detection pilot signals,   wherein a directional gain of the estimation pilot signals is the same as that of the detection pilot signals.   
     
     
         8 . The base station according to  claim 7 , wherein the base station transmits the generated estimation pilot signals and the generated detection pilot signals after multiplexing said signals. 
     
     
         9 . The base station according to  claim 7 , wherein the estimation pilot signals are transmitted for a time period which is longer than a time period of the detection pilot signals.