A user equipment includes a receiver configured to receive a PDSCH and a transmitter configured to transmit a HARQ-ACK response for a serving cell. In a first case that the user equipment communicates with at least a serving cell having a duplex mode that is TDD, the transmitter is configured to transmit, in a primary cell, the HARQ-ACK response in an uplink subframe n upon detection of a PDSCH transmission in the serving cell within a subframe nk. In a second case that the user equipment communicates with a primary cell and a secondary cell, duplex mode of the primary cell being FDD, the transmitter is configured to transmit, in the primary cell, the HARQ-ACK response in an uplink subframe m upon detection of a PDSCH transmission in the secondary cell in only a subframe m4.

Methods and apparatus are described for a User Equipment (UE) to determine a set of resources available for transmitting an acknowledgement signal in an UpLink (UL) Component Carrier (CC) in response to reception of multiple DownLink (DL) Scheduling Assignments (SAs) transmitted from a base station with each DL SA being associated with a respective DL CC. The UL CC and a first DL CC establish a communication link when the UE is configured for communication over a single UL CC and a single DL CC.

Disclosed herein are implementations of a hybrid network for use in a full duplex communication system. In one aspect, the hybrid network includes a first circuit coupled between an output of a communication channel and a shared output of a transmitter and the communication channel, a second circuit coupled between a first output of the transmitter and the shared output, a third circuit coupled between the shared output and an input of an amplifier, a fourth circuit coupled between the input of the amplifier and a second output of the transmitter, and a fifth circuit coupled between an output of the amplifier and the input of the amplifier. In some embodiments, the output of the amplifier is coupled to an input of a receiver.

A user terminal carries out radio communication with a plurality of cells by employing carrier aggregation, and has a receiver that, when a connection is established with a TDD cell, receives information about a given DL/UL configuration that is selected from a plurality of DL/UL configurations, and a processor that controls transmission and reception to and from the TDD cell, and a DL/UL configuration to carry out DL communication in all subframes is included as one in the plurality of DL/UL configurations, and the processor uses the DL/UL configuration to carry out DL communication in all subframes as one of the DL/UL configurations only when the connecting TDD cell is a secondary cell. If so, the processor feeds back an A/N in response to each DL subframe of the secondary cell by using a given UL subframe of a primary cell.

Embodiments of the present invention provide an uplink control information transmission method, a base station, and user equipment. The method includes: receiving, by UE in a downlink subframe N, a downlink control channel sent by a base station; sending, by the UE, a hybrid automatic repeat request-acknowledgement corresponding to the downlink control channel to the base station in an uplink subframe N+4 by using a PUCCH, where when the uplink subframe N+4 belongs to a first uplink subframe set, the PUCCH is carried on a second serving cell of the UE, and when the uplink subframe N+4 belongs to a second uplink subframe set, the PUCCH is carried on the first serving cell, where a duplexing mode of the first serving cell is different from a duplexing mode of the second serving cell.

The present disclosure relates to a method and an apparatus for transmitting a control channel in an intra-cell carrier aggregation system. The method includes establishing a connection with a base station through a Primary cell (Pcell) of a Time Division Duplex (TDD) scheme and a Secondary cell (Scell) of a Frequency Division Duplex (FDD) scheme. The method also includes receiving data through the Scell before a timing configured as an uplink sub-frame according to a TDD UpLink-DownLink (UL-DL) configuration of the Pcell. The method also includes transmitting a feedback of the received data through the Pcell in a feedback sub-frame. By the method, a feedback for a data can be effectively transferred.

Provided are a method for performing a hybrid automatic repeat request (HARQ) in a wireless communication system, and a wireless device using the same. The wireless device receives at least one downlink (DL) transmission block from at least one DL sub-frame in a frequency division duplex (FDD) cell and transmits ACK/NACK corresponding to the at least one DL transmission block from an uplink (UL) HARQ sub-frame in a time division duplex (TDD) cell. The UL HARQ sub-frame belongs to a subset of a set of UL sub-frames determined according to the UL-DL setting of the TDD cell.

Disclosed herein are implementations of a hybrid network for use in a full duplex communication system. In one aspect, the hybrid network includes a first circuit coupled between an output of a communication channel and a shared output of a transmitter and the communication channel, a second circuit coupled between a first output of the transmitter and the shared output, a third circuit coupled between the shared output and an input of an amplifier, a fourth circuit coupled between the input of the amplifier and a second output of the transmitter, and a fifth circuit coupled between an output of the amplifier and the input of the amplifier. In some embodiments, the output of the amplifier is coupled to an input of a receiver.

A method and apparatus for transmitting control information in a wireless communication system supporting carrier aggregation (CA) is disclosed. A method for transmitting control information to a base station (BS) by a user equipment (UE) in a wireless communication system includes receiving at least one of a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) from the base station through at least one serving cell configured in the user equipment, and transmitting control information regarding PDCCH reception or PDSCH reception indicated by the PDCCH to the base station. The control information is transmitted through a physical uplink control channel (PUCCH) of a primary cell, using control information feedback timing of at least one of the primary cell and a first cell of the at least one serving cell, and the at least one serving cell uses different uplink and downlink (UL-DL) configurations.

A wireless transmit/receive unit (WTRU) includes a receiver and a processor configured to receive information from a network node indicating an assignment of periodic time intervals to transmit sounding signals. The WTRU includes a transmitter and the processor configured to transmit sounding signals to the network node in the assigned periodic time intervals in response to the received information. The WTRU does not transmit any data at a same time that the WTRU transmits the sounding signals. The transmitted sounding signals from the WTRU are distinguishable from sounding signals from other WTRUs.