Base station apparatus and terminal device

Abstract

In an LTE-A system, there is a problem that it is difficult to perform stable communication in a case where there is a time when another system occupies an unlicensed band being used. There is provided a base station apparatus that communicates with a terminal device in a second frequency band different from a first frequency band capable of being used as a dedicated frequency band. The base station apparatus includes: a wireless transmission unit that transmits data or control information to the terminal device; and a wireless reception unit that receives data or control information transmitted from the terminal device. The wireless transmission unit transmits data to the terminal device, and the wireless reception unit performs a process of receiving ACK/NACK transmitted from the terminal device in a subframe of an initial uplink after communication of another system is ended in a case where the other system performs the communication in the second frequency band at a reception timing of the ACK/NACK of the data transmission.

1 . A base station apparatus that communicates with a terminal device in a second frequency band different from a first frequency band capable of being used as a dedicated frequency band, the base station apparatus comprising:
 a wireless transmission unit that transmits data or control information to the terminal device; and   a wireless reception unit that receives data or control information transmitted from the terminal device,   wherein the wireless transmission unit transmits data to the terminal device, and the wireless reception unit performs a process of receiving ACK/NACK transmitted from the terminal device in a subframe of an initial uplink after communication of another system is ended in a case where the other system performs the communication in the second frequency band at a reception timing of the ACK/NACK of the data transmission.   
     
     
         2 . The base station apparatus according to  claim 1 ,
 wherein the wireless transmission unit transmits control information of resource allocation for data transmission of the terminal device, and the wireless reception unit performs a process of receiving data transmitted from the terminal device in a subframe of an initial uplink after communication of another system is ended in a case where the other system performs the communication in the second frequency band at a reception timing of data of the resource allocation.   
     
     
         3 . A base station apparatus that communicates with a terminal device in a first frequency band capable of being used as a dedicated frequency band and a second frequency band different from the first frequency band, the base station apparatus comprising:
 a wireless transmission unit that transmits data or control information to the terminal device; and   a wireless reception unit that receives data or control information transmitted from the terminal device,   wherein the wireless transmission unit transmits data to the terminal device, and the wireless reception unit performs a process of receiving ACK/NACK transmitted from the terminal device in the first frequency band in a case where another system performs communication in the second frequency band at a reception timing of ACK/NACK of the data transmission.   
     
     
         4 . The base station apparatus according to  claim 3 ,
 wherein the wireless reception unit receives data transmitted from the terminal device, and ACK/NACK is transmitted to the terminal device in the first frequency band in a case where another system performs communication in the second frequency band at a transmission timing of ACK/NACK of the data transmission.   
     
     
         5 . The base station apparatus according to  claim 3 , further comprising:
 a data amount management unit that manages a buffered data amount of a downlink,   wherein the wireless transmission unit notifies of a NAV by using RTS or CTS-to-self or transmits dummy data in a case where there is not the buffered data amount of the downlink.   
     
     
         6 . A terminal device that communicates with a base station apparatus in a second frequency band different from a first frequency band capable of being used as a dedicated frequency band, the terminal device comprising:
 an available subframe determination unit that detects a synchronization signal transmitted from the base station apparatus;   a reception signal detection unit that performs a process of receiving a data signal transmitted from the base station apparatus; and   a wireless transmission unit that transmits a signal to the base station apparatus,   wherein, in a case where ACK/NACK indicating whether or not the data signal transmitted from the base station apparatus is normally received by the reception signal detection unit is transmitted, the wireless transmission unit transmits the ACK/NACK in an uplink subframe after four subframes from a timing when the data signal is received and after notification indicating that another system does not perform communication in the second frequency band is received by the available subframe determination unit from the base station apparatus.   
     
     
         7 . The terminal device according to  claim 6 , further comprising:
 a control signal detection unit that detects control information including resource allocation used for data transmission to the base station apparatus,   wherein, in a case where the control signal detection unit detects control information including resource allocation used for data transmission transmitted from the base station apparatus, the wireless transmission unit transmits data to the base station apparatus in an uplink subframe after four subframes from a timing when the resource allocation is received and after notification indicating that another system does not perform communication in the second frequency band is received from the base station apparatus.   
     
     
         8 . The terminal device according to  claim 6 , further comprising:
 a wireless reception unit that performs carrier sense for determining whether or not another system performs communication in the second frequency band,   wherein the wireless reception unit performs carrier sense in a subframe switched from a downlink to an uplink.   
     
     
         9 . The terminal device according to  claim 8 ,
 wherein the subframe switched to the uplink from the downlink in which the wireless reception unit performs the carrier sense is a subframe switched to an uplink from a downlink before a subframe in which the ACK/NACK of downlink data or data transmitted to the base station apparatus is transmitted.   
     
     
         10 . The terminal device according to  claim 8 ,
 wherein the wireless reception unit performs carrier sense in only a frequency band in which the ACK/NACK of downlink data or data transmitted to the base station apparatus is transmitted.   
     
     
         11 . The terminal device according to  claim 8 ,
 wherein, in a case where the synchronization signal transmitted from the base station apparatus is not able to be detected by the available subframe determination unit or another system performs communication in the second frequency band as a result of the carrier sense of the wireless reception unit, the wireless reception unit uses the first frequency band for the transmission of the ACK/NACK of downlink data or data transmitted to the base station apparatus.