User terminal, radio base station and radio communication method

Abstract

The present invention is designed to improve throughput and support various modes of use of radio communication systems when TDD is used in an environment in which the data traffic is unevenly concentrated on the downlink. A user terminal carries out radio communication with a TDD cell, and has a transmitting/receiving section that transmits and receives signals by using a UL/DL configuration, which includes a special subframe formed with a downlink time duration, a guard period and an uplink time duration, and in which DL communication is carried out in all subframes, and a control section that controls the arrangement of uplink demodulation reference signals based on the length of the uplink time duration constituting the special subframe.

1 . A user terminal that carries out radio communication with a TDD cell, comprising:
 a transmitting/receiving section that transmits and receives signals by using a UL/DL configuration, which includes a special subframe formed with a downlink time duration, a guard period and an uplink time duration, and in which DL communication is carried out in all subframes; and   a control section that controls an arrangement of an uplink demodulation reference signal based on a length of the uplink time duration constituting the special subframe.   
     
     
         2 . The user terminal according to  claim 1 , wherein the control section configures two uplink demodulation reference signals when the number of symbols of the uplink time duration is equal to or greater than a predetermined value. 
     
     
         3 . The user terminal according to  claim 2 , wherein the control section makes a distance between the two uplink demodulation reference signals greater as the number of symbols of the uplink time duration increases. 
     
     
         4 . The user terminal according to  claim 2 , wherein the control section changes a location to allocate one of the uplink demodulation reference signals depending on the length of the uplink time duration, and fixes a location to allocate the other one of the uplink demodulation reference signals regardless of the length of the uplink time duration. 
     
     
         5 . The user terminal according to  claim 2 , wherein the control section allocates one of the uplink demodulation reference signals to a top symbol to constitute the uplink time duration, and fixes a location to allocate the other one of the uplink demodulation reference signals. 
     
     
         6 . The user terminal according to  claim 4 , wherein the control section allocates the other one of the uplink demodulation reference signals to a tenth symbol in the special subframe. 
     
     
         7 . The user terminal according to  claim 1 , wherein the control section controls allocation of uplink control information to a neighboring symbol of a symbol where the uplink demodulation reference signal is allocated. 
     
     
         8 . A radio base station that communicates with a user terminal connected with at least a TDD cell, the radio base station comprising:
 a selection section that selects, as a UL/DL configuration for use by the user terminal, a UL/DL configuration, includes a special subframe formed with a downlink time duration, a guard period and an uplink time duration, and in which DL communication is carried out in all subframes; and   a control section that controls allocation of uplink control information to allocate to the special subframe, based on an arrangement of an uplink demodulation reference signal configured in association with a length of the uplink time duration.   
     
     
         9 . A radio communication method in a user terminal that carries out radio communication with a TDD cell, the radio communication method comprising:
 determining use of a UL/DL configuration, which includes a special subframe formed with a downlink time duration, a guard period and an uplink time duration, and in which DL communication is carried out in all subframes; and   controlling an arrangement of an uplink demodulation reference signal based on a length of the uplink time duration constituting the special subframe.   
     
     
         10 . (canceled) 
     
     
         11 . The user terminal according to  claim 5 , wherein the control section allocates the other one of the uplink demodulation reference signals to a tenth symbol in the special subframe.