An evolution of radio access schemes and radio networks for cellular mobile communication (hereinafter referred to as “Long Term Evolution (LTE)” or “Evolved Universal Terrestrial Radio Access (EUTRA)”) is being studied by the 3rd Generation Partnership Project (3GPP). In LTE, the Orthogonal Frequency Division Multiplexing (OFDM) scheme, which is a multi-carrier transmission scheme, is used as a communication scheme for wireless communication from a base station device to a mobile station device (downlink). Also, the Single-Carrier Frequency Division Multiple Access (SC-FDMA) scheme, which is a single-carrier transmission scheme, is used as a communication scheme for wireless communication from a mobile station device to a base station device (uplink).
In LTE, an ACK (Acknowledgement)/NACK (Negative Acknowledgement) (also referred to as HARQ-ACK), which indicates whether or not a mobile station device has succeeded in decoding downlink data received on the Physical Downlink Shared Channel (PDSCH), is transmitted on the Physical Uplink Control Channel (PUCCH) or Physical Uplink Shared Channel (PUSCH). In a case where the mobile station device is not allocated radio resources for the PUSCH when transmitting an ACK/NACK, the ACK/NACK is transmitted on the PUCCH. In a case where the mobile station device is allocated radio resources for the PUSCH when transmitting an ACK/NACK, the ACK/NACK is transmitted on the PUSCH. In LTE, in a case where an ACK/NACK of 3 bits or more is to be transmitted on the PUSCH, the ACK/NACK is encoded using Reed-Muller code to generate an encoded ACK/NACK bit sequence of 32 bits.
In 3GPP, studies are being performed to allow radio access schemes and radio networks which realize higher-speed data communication using a broader frequency band than that of LTE (hereinafter referred to as “Long Term Evolution-Advanced (LTE-A)” or “Advanced Evolved Universal Terrestrial Radio Access (A-EUTRA)”) to have backward compatibility with LTE. That is, a base station device of LTE-A is capable of simultaneously performing wireless communication with mobile station devices of both LTE-A and LTE, and a mobile station device of LTE-A is capable of performing wireless communication with base station devices of both LTE-A and LTE. The channel structure of LTE-A is the same as that of LTE.
In LTE-A, there is suggested a technology in which a plurality of frequency bands having the same channel structure as LTE (hereinafter referred to as “component carriers (CCs)”) or a plurality of cells are used as one frequency band (broad frequency band). This is also referred to as, for example, carrier aggregation or cell aggregation. For example, in communication using frequency band aggregation, a base station device is capable of simultaneously transmitting a plurality of Physical Downlink Control Channels (PDCCHs) and a plurality of Physical Downlink Shared Channels (PDSCHs) to a mobile station device using one or a plurality of downlink component carriers (DL CCs) or cells, and the mobile station device is capable of simultaneously receiving the plurality of PDCCHs and PDSCHs.
In LTE-A, studies are being performed on dividing ACKs/NACKs into two ACK/NACK segments and separately encoding the two ACK/NACK segments using Reed-Muller code in the case of transmitting ACKs/NACKs which are larger than 11 bits and smaller than 22 bits using the Physical Uplink Control Channel (PUCCH) (NPL 1).
NPL 2 suggests a technology in which a mobile station device executes spatial bundling on individual ACKs/NACKs for a plurality of pieces of downlink data which have been multiplexed to a single PDSCH by a base station device using spatial domain multiplexing (SDM), thereby generating one ACK/NACK. Here, bundling of ACKs/NACKs (ACK/NACK bundling) means, for example, a mobile station device executes logical AND operation on a plurality of ACKs/NACKs (for individual PDSCH transmissions) to generate a smaller number of ACKs/NACKs (for example, expressed by 1 bit).
For example, in a case where all of a plurality of ACKs/NACKs to be bundled are ACKs, a mobile station device generates one ACK as bundled ACKs/NACKs and transmits the ACK to a base station device. Also, for example, in a case where a plurality of ACKs/NACKs to be bundled include at least one NACK, the mobile station device generates one NACK as bundled ACKs/NACKs and transmits the NACK to the base station device. If the base station device receives ACKs bundled by the mobile station device, the base station device determines that all of the plurality of ACKs/NACKs corresponding to bundled ACKs/NACKs are ACKs. Also, if the base station device receives NACKs bundled by the mobile station device, the base station device determines that at least one NACK is included in the plurality of ACKs/NACKs corresponding to bundled ACKs/NACKs.
NPL 3 suggests a technology in which a mobile station device executes spatial bundling on ACKs/NACKs corresponding to a plurality of pieces of downlink data, and also executes time-domain bundling and/or component-carrier-domain bundling on the ACKs/NACKs on which spatial bundling has been executed. Here, time-domain bundling means that a mobile station device executes ACK/NACK bundling on ACKs/NACKs for the PDSCH which have been respectively received in a plurality of subframes in a certain cell. Component-carrier-domain bundling means that a mobile station device executes ACK/NACK bundling on ACKs/NACKs for the PDSCH which have been respectively received in a plurality of cells (component carriers) in a certain subframe.