A wireless access method and a wireless network in cellular mobile communication (hereinafter referred to as “Long Term Evolution (LTE)” or “Evolved Universal Terrestrial Radio Access (EUTRA)”) have been under consideration by 3rd Generation Partnership Project (3GPP). In LTE, orthogonal frequency division multiplexing (OFDM) is used as a downlink communication method. Furthermore, in LTE, SC-FDMA (Single-Carrier Frequency Division Multiple Access) is used as an uplink communication method. In LTE, a base station apparatus is called eNodeB (evolved NodeB), and a mobile station apparatus (a terminal apparatus) is called UE (User Equipment). The LTE is a cellular communication system in which a plurality of areas covered by respective base station apparatuses are disposed in the form of cells. One base station apparatus may manage a plurality of cells. One mobile station apparatus is allowed to make communication in one or a plurality of cells. The cell is also called a serving cell.
LTE supports HARQ (Hybrid Automatic Repeat reQuest) for uplink data. In LTE, when a mobile station apparatus successfully decodes a transport block received via a PDSCH (Physical Downlink Shared Channel), the mobile station apparatus transmits ACK (positive acknowledgement, acknowledgement) in terms of this transport block via PUCCH (Physical Uplink Control Channel). On the other hand, in LTE, when a mobile station apparatus fails to decode a transport block received via the PDSCH, the mobile station apparatus transmits NACK (negative acknowledgement) in terms of this transport block via a PUCCH (Physical Uplink Control Channel).
In LTE, a base station apparatus performs scheduling on a transport block based on ACK or NACK received via a PUCCH. For example, when the base station apparatus in LTE receives NACK, the base station apparatus retransmits the transport block. ACK and NACK are collectively referred to as HARQ-ACK or HARQ feedback.
The LTE base station apparatus transmits downlink control information used in the scheduling on PDSCH via PDCCH (Physical Downlink Control Channel) or EPDCCH (Enhanced Physical Downlink Control Channel).
The LTE base station apparatus sets one or two EPDCCH-PRB-sets to the terminal apparatus. The EPDCCH-PRB-set is a set of physical resource blocks including physical resource blocks (PRBs) used by the terminal apparatus to monitor EPDCCH. Monitoring implies attempting to decode EPDCCH.
The LTE base station apparatus is capable of setting a first parameter corresponding to a first EPDCCH-PRB-set and a second parameter corresponding to a second EPDCCH-PRB-set to the mobile station apparatus. Using a parameter corresponding to an EPDCCH-PRB-set via which EPDCCH is detected, the LTE mobile station apparatus determines a PUCCH resource to be used in transmitting HARQ-ACK. This makes it possible for the LTE base station apparatus to flexibly control the allocation of PUCCH resources (NPL 1).
In 3GPP, to allow a mobile station apparatus to communicate with a plurality of transmission/reception points in an efficient manner, support for CoMP (Coordinated Multi-Point transmission and reception) is under consideration. For example, a mobile station apparatus may receive PDSCH transmitted from a plurality of transmission points. The plurality of transmission/reception points may be controlled by a single base station apparatus or different two or more base station apparatuses.