DESCRIPTION METHOD FOR TRANSMITTING UPLINK CONTROL INFORMATION, WIRELESS TERMINAL, AND BASE STATION 5 Technical Field [0001] The present application relates to a wireless communication system and, particularly, to transmission of uplink control information from a wireless terminal 10 to a base station. Background Art [0002] The structure of a radio frame used in 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), t ime division duplex (TDD), and the 15 overview of uplink transmission are described hereinafter. Further, enhanced interference mitigation and traffic adaptat ion (eIMTA) , which has been recently discussed in 3GPP Release 12, is described. [0003] The LTE radio frame structure is described first . In 3GPP Release 8 and 20 later (i .e., LTE), two types of radio frame structures are defined. One is called frame structure type 1, which is applicable to frequency division duplex (FDD) . The other is called frame structure type 2, which is appl icable to TDD. As shown in Fig. 1, in the frame structures of both type 1 and type 2, the length of one radio frame is 10 ms, and one radio frame is composed of 10 subframes. In the case of 25 TDD, the first 5 subframes (#0 to #4) and the latter 5 subframes (#5 to #9) are collectively called half frames. The length of each half frame is 5 ms. The length of one subframe is 1 ms. Further, one subframe is divided into two slots, each having the length of 0.5 ms. In the case of the normal cyclic prefix, one slot includes 7 symbols (single carrier frequency division mult iple access (SC-FDMA) 30 symbols for uplink; orthogonal frequency division multiplexing (OFDM) symbols for downl ink). Thus, one subframe includes 14 symbols in the time domain. [0004] 3 Fig. 2 shows radio resources where not only the time domain but also the frequency domain are taken into considerat ion. The smallest resource unit is the resource element , which consists of one symbol time in the time domain and one subcarrier in the frequency domain. The subcarrier interval is 15 kHz. The 5 radio resource allocat ion of uplink and downlink is done in uni ts of two consecut ive resource blocks (subframe time length). One res ource block has 7 symbols (0.5 ms) which corresponds to half of one subframe in the time domain and has 12 subcarriers in the frequency domain. [0005] 10 The upl ink-downl ink configurations (UL-DL configurations) supported by TDD LTE are described hereinbelow. In the case of TDD LTE, uplink subframes (UL subframes) and downlink subframes (DL subframes) coexist in one radio frame. Each UL subframe is a subframe in which uplink transmission from a wireless terminal to a base station is performed, and each DL subframe is a 15 subframe in which downlink transmission from a base station to a wireless terminal is performed. The UL-DL configurations provide different placements of uplink subframes and downlink subframes in one radio frame. [0006] Fig. 3 shows seven uplink-downlink configurations (UL-DL 20 configurations) disclosed in Non Patent Literature 1. In Fig. 3, "D" indicates a DL subframe, "U" indicates a UL subframe, and "S" indicates a special subframe. The switching from downlink transmission (DL subframe s) to uplink transmission (UL subframes) is made in the second subframe in the half frame (i.e., in the subframes #1 and #6) . When the switching from downlink transmission (DL 25 subframes) to uplink transmission (UL subframes) is made, special subframes are placed. The special subframe is composed of a downlink pilot time slot (DwPTS) where downlink transmission is performed, a guard period (GP) where no transmission is performed, and an uplink pilot time slot (UpPTS) where uplink transmission is performed. In TDD LTE, any one of the UL-DL configurations 30 shown in Fig. 3 is used with radio frame periodicity (10 ms). [0007] The transmission of uplink control information (UCI) from a wireless terminal to a base station in 3GPP Release 8 and later (i.e. , LTE) is described hereinbelow. The UCI can contain control information related to downlink 4 communicat ion. The control information related to downlink communicat ion includes hybrid automatic repeat request (HARQ) ACK/NACK and channel state information (CSI). The CSI contains channel quality Indicator s (CQIs) for link adaptation, and may further contain feedback related to multiple-input and 5 multiple-output (MIMO) (i .e., pre-coding matrix indicators (PMIs) and rank indicators (RIs)). [0008] When the UCI is transmitted in a subframe where no radio resource is allocated for a physical uplink shared channel (PUSCH) , UCI is transmitted on a 10 physical uplink control channel (PUCCH). On the other hand, when the UCI is transmitted in a subframe where radio resources are allocated for a PUSCH, UCI is transmitted on the PUSCH. The PUCCH is never transmitted in the same subframe as the PUSCH in 3GPP Releases 8 and. This is because, if the PUCCH and the PUSCH are simultaneously transmitted in the same subframe, the 15 peak-to-average power ratio (PAPR) of uplink transmission signals increases. To be specific, the UCI is multiplexed on uplink shared channel (UL-SCH) data (i .e. , a transport channel containing user data) prior to DFT spreading for generating a SC-FDMA signal (discrete Fourier transform spread OFDM (DFTS-OFDM) signal). Note that , in 3GPP Release 10 and later, a transmission mode for simultaneously 20 transmitting the PUSCH and the PUCCH in the same subframe is defined. However, because this transmission mode causes an increase in the PAPR as described above, i t is generally applied only to a small number of wireless terminals located near a base station. Therefore, in 3GPP Release 10 and later also, wireless terminals at a long distance from a base station generally use the 25 transmission mode where the UCI is multiplexed on UL-SCH data and then transmitted in the PUSCH (which is the transmission mode to suppress the PAPR). [0009] Fig. 4 shows one example of processing for mul tiplexing UCI ( i .e. , CQI/PMI, HARQ ACK/NACK and RI) on resource elements scheduled for the 30 PUSCH together wi th UL-SCH data symbols. Note that Fig. 4 shows 168 resource elements corresponding to 2 resource blocks consisting of 14 symbols and 12 subcarriers. As shown in Fig. 4, reference signals (RSs) 41 (i.e., demodulation reference symbols (DMRSs)) is placed on the fourth SC-OFDMA (DFTS-OFDM) symbol of each slot . As shown in Fig. 4, coded CQI/PMI symbols 43 are placed 5 at the beginning of available radio resources so as to sequentially occupy SC-FDMA symbols of one subcarrier. In order to prevent UL-SCH data from being punctured for CQI/PMI transmission, UL-SCH data is rate-matched around CQI/PMI bits so that it can be transmitted in the remaining radio resources 42. 5 Coded HARQ ACK/NACK symbols 44 are placed next to SC-FDMA symbols of the reference signals (RSs) 41 by puncturing UL-SCH data in a channel interleaver. Coded RI symbols 45 are placed next to the positions of HARQ ACK/NACK symbols 44 shown in Fig. 4 regardless of whether the HARQ ACK/NACK symbols 44 actually exist in the current subframe. 10 [0010] The number of resource elements (the number of coded symbols) used for each of CQI/PMI, HARQ ACK/NACK and RI is determined in a wireless terminal based on modulation and coding scheme (MCS) of PUSCH (i .e. , modulation order (Qm)) and of fs et p ar amet ers βCQI of f s et , βHARQ-ACK of f s et and βRI of f s et . The offset paramet ers βCQI of f s et , βHARQ-ACK of f set and βRI 15 of f s et are configured in a semi-static manner in upper-layer signaling between the wireless terminal and a base station (to be specific, RRC setup procedure) . Specifically, as described in Sect ion 8.6.3 of Non Patent Li terature 3, in order to notify the UE of the offset parameters βCQI of f s et , βHARQ-ACK of f s et and βRI of f s et , the base station transmits to the UE a set of indices ICQI of f s et, IHARQ-ACK of f s et and IRI 20 of f s et which are associated with the values of the offset parameters. [0011] As described in Section 5.2.2.6 of Non Patent Literature 2, the number of resource elements (the number of coded symbols) used for HARQ ACK/NACK and 25 RI when PUSCH transmission is performed is determined using the following Equation (1): [0012] In the above Equation (1) , Q’ is the number of coded symbols. O is the number of HARQ ACK/NACK bits or RI bits. MPUSCH 30 sc is the number of subcarriers scheduled for physical uplink shared channel (PUSCH) transmission in min , 4 (1) 1 0                                     PUSCH C sc r r PUSCH offset PUSCH initial symb PUSCH initial sc M K O M N Q  6 the current subframe for a transport block. NPUSCH- ini t ial symb is the number of single-carrier frequency division mult iple access (SC-FDMA) symbols per subframe for init ial PUSCH transmission for the same transport block. MPUSCH- ini t ial sc, C, and Kr are parameters obtained from ini tial physical downl ink 5 control channel (PDCCH) transmission for the same transport block. To be specific, MPUSCH- ini t ial sc is the number of allocated subcarriers at initial PUSCH transmission, C is the number of code blocks, and Kr is the code block size of a code block index #r. Further, βPUSCH of f s et is an offset parameter, and βHARQ-ACK of f set i s us ed in the case of HARQ ACK/NACK, and β RI of f s et is used in the 10 case of RI. [0013] Further, as described in Section 5.2.2.6 of Non Patent Literature 2, the number of resource elements (the number of coded symbols) used for CQI/PMI when PUSCH transmission is performed is determined using the following 15 Equation (2): [0014] In the above Equation (2) , Q’ is the number of coded symbols. O is the number of CQI bits. L is the number of cyclic redundancy check (CRC) bits appl ied to CQI/PMI. MPUSCH 20 sc is the number of subcarriers scheduled for physical uplink shared channel (PUSCH) transmission in the current subframe for a transport block. NPUSCH symb is the number of single-carrier frequency division multiple access (SC-FDMA) symbols for the PUSCH transmission in the current subframe. NPUSCH- in i t ial symb is the number of SC-FDMA symbols per subframe for 25 initial PUSCH transmission for the same transport block. QRI is the number of rank indicator bits transmi tted in the current subframe. Qm is the number of transmission bits per symbol in a modulat ion scheme applied to the PUSCH. MPUSCH- ini t ial sc, C, and Kr are parameters obtained from ini tial physical downl ink control channel (PDCCH) transmission for the same transport block. To be specific, MPUSCH- ini t ial 30 sc is the number of al located subcarriers at initial PUSCH transmission, C is the number of code blocks, and Kr is the code block size of a , (2) ( ) min 1 0                                       m PUSCH RI symb PUSCH C sc r r PUSCH offset PUSCH initial symb PUSCH initial sc Q Q M N K O L M N Q  7 code block index #r. Further, βPUSCH of f s et is an offset parameter, and βCQI of f s et is used in the case of CQI/PMI. [0015] A wireless terminal determines, based on the above Equation (1) or (2), the 5 number of coded symbols Q’ for each of HARQ ACK/NACK, RI and CQI/PMI in channel coding of upl ink information channel (UCI). The wireless terminal then determines the number of coded HARQ ACK/NACK bits, the number of coded RI bits and the number of coded CQI/PMI bi ts based on modulation order (Qm) allocated to PUSCH and the number of coded symbols Q’, in accordance with the 10 following Equations (3) to (5). After that , the wireless terminal performs channel coding, i.e. circular repetition or repetition coding, for HARQ ACK/NACK bits, RI bits and CQI/PMI bits based on the determined number of coded HARQ ACK/NACK bits, the determined number of coded RI bits and the determined number of coded CQI/PMI bits. 15 [0016] Processing on a transport channel UL-SCH and UCI for generating a 20 physical channel PUSCH described in Non Patent Literatures 1 and 2 is described hereinafter with reference to Fig. 5. Because channel coding of the UCI is mainly focused here, the illustration of transport block CRC attachment, code block segmentation and code block CRC attachment, channel coding of UL-SCH, rate matching, and code block concatenat ion for UL-SCH data bits (transport block) is 25 omitted. [0017] A channel coding uni t 501 performs channel coding on CQI/PMI bits and thereby generates coded CQI/PMI bi ts. A channel coding uni t 502 performs channel coding on RI bit(s) and thereby generates coded RI bits. A channel 30 coding unit 503 performs channel coding on HARQ ACK/NACK bit( s) and thereby generates coded HARQ ACK/NACK bi ts. The channel coding units 501 to 503 determine th e number o f co ded s ymbol s Q’ for UCI according to the above   (3) HARQ ACK offset PUSCH ACK m offset Q Q Q and          (4) RI offset PUSCH RI m offset Q Q Q and      (5) CQI offset PUSCH CQI m offset Q Q Q and    8 Equation (1) or (2), determine the number of coded UCI bits, and then perform channel coding in accordance with the number of coded UCI bits. [0018] A mult iplexer 504 multiplexes coded UL-SCH data bits and coded 5 CQI/PMI bits so that the coded CQI/PMI symbols 43 are mapped at the beginning of available radio resources as shown in Fig. 4. [0019] A channel interleaver 505 performs interleaving on the output bits of the multiplexer 504, the coded HARQ ACK/NACK bits , and the coded RI bits so that 10 the HARQ ACK/NACK symbols 44 and the coded RI symbols 45 are placed around the reference signal (RS) 41 in the time domain as shown in Fig. 4. [0020] A scrambler 506 mult iplies the outputs bits of the channel interleaver 505 by a scrambling sequence. A modulator 507 maps the block of the scrambled bits 15 to modulated symbols and thereby generates a modulated symbol sequence. A resource element mapper 508 maps the modulated symbol sequence to resource elements in a resource block allocated for PUSCH transmission. [0021] A SC-FDMA signal generator 509 generates an SC-FDMA signal from the 20 modulated symbol sequence. Specifically, the SC-FDMA signal generator 509 performs DFT spreading on M number of modulated symbols corresponding to the radio resources allocated in one subframe, maps M number of frequency domain signals after DFT spreading to subcarriers in accordance with the mapping by the resource element mapper 508, and then generates an SC-FDMA signal 25 (DFTS-OFDM signal) by performing N-point inverse fast Fourier transform (IFFT) . Note that , because M