The following documents and standards descriptions are hereby incorporated into the present disclosure as if fully set forth herein: [1] 3GPP Technical Specification No. 36.212: “Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding”; [2] 3GPP Technical Specification No. 36.213: “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures”; [3] 3GPP Technical Specification No. 36.211: “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation”; [4] 3GPP Technical Report No. 36.814, “Further Advancements for E-UTRA; Physical Layer Aspects”; [5] 3GPP Technical Report No. 36.912, “Feasibility Study for Further Advancement for E-UTRA (LTE-Advanced)”; [6] 3GPP Technical Report No. 21.905: “Vocabulary for 3GPP Specifications”; [7] 3GPP Technical Specification No. 36.201: “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Layer—General Description”; [8] 3GPP Technical Specification No. 36.214: “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer—Measurements”; [9] 3GPP Technical Specification No. 36.321, “Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) protocol specification”; [10] R1-102210, ‘Discussions on UL MIMO Signalling Requirements,” 3GPP TSG RAN WG1 Meeting #60bis, Beijing, China, Apr. 12-16, 2010; Eli) R1-102210, ‘Discussions on UL MIMO Signalling Requirements,” 3GPP TSG RAN WG1 Meeting #60bis, Beijing, China, Apr. 12-16, 2010; [12] R1-101731, Ericsson and ST-Ericsson, “Evaluation of PUCCH Proposals for Carrier Aggregation,” 3GPP TSG-RAN WG1 Meeting #60bis, Beijing, China, 12-16 Apr., 2010; and [13] U.S. Provisional Application No. 61/370,765, filed on Aug. 4, 2010, entitled “Methods and Apparatus for Uplink Control Channel Transmission,” by Hoang Nguyen and Zhouyue (Jerry) Pi.
In Rel. 8/9 LTE standard ([1], [2], [3]), the physical uplink control channel (PUCCH) is used to transport control information from the mobile terminal (UE) to the base station (eNB). There are several PUCCH formats with different code block sizes as shown in Table 1. Control information transported on the PUCCH include acknowledgment (ACK) or negative acknowledgment (NACK) information, wide-band channel quality indicator (CQI), UE-selected sub-band CQI, rank indicator (RI), and precoding matrix index (PMI). Shown in Table 2 and Table 3 is the bit width of some of these information fields for transmission modes 4, 5 and 6.
For PUCCH formats 1a and 1b, one or two explicit ACK/NACK bits are transmitted, respectively, using repetition error control encoding. For PUCCH formats 2/2a/2b, a (20, A) Reed-Muller channel code, whose generator matrix is shown in Table 4, is used to generate the first 20 channel bits. The 20 channel bits are quadrature phase-shift keying (QPSK) modulated into 10 modulation symbols. For PUCCH formats 2a and 2b, the 11th modulation symbol is obtained from the ACK/NACK bits according to Table 5.
TABLE 1Code block size of LTE Rel. 8/9 PUCCH formats[3].PUCCHModulationNumber of code bitsformatschemeper subframe1N/AN/A1aBPSK11bQPSK22QPSK202aQPSK + BPSK212bQPSK + QPSK22
TABLE 2Uplink Control Information (UCI) fields forchannel quality indicator and precoding matrix indicator (CQI/PMI)feedback for wideband reports (transmission mode 4, transmissionmode 5 and transmission mode 6) [1].Bit width2 antenna ports4 antenna portsFieldRank = 1Rank = 2Rank = 1Rank > 1Wide-band CQI4444Spatial0303differential CQIPrecoding matrix2144indication
TABLE 3UCI fields for CQI/PMI feedback for UE-selectedsub-band reports (transmission mode 4, transmission mode 5 andtransmission mode 6) [1].Bit width2 antenna ports4 antenna portsFieldRank = 1Rank = 2Rank = 1Rank > 1Wide-band CQI4444Spatial0303differential CQIPrecoding matrix2144indication
TABLE 4Basis sequences for (20, A) code [1].iMi,0Mi,1Mi,2Mi,3Mi,4Mi,5Mi,6Mi,7Mi,8Mi,9Mi,10Mi,11Mi,1201100000000110111100000011102100100101111131011000010111411110001001115110010111011161010101011111710011001101118110110010111191011101001111101010011101111111110011010111121001010111111131101010101111141000110100101151100111101101161110111001011171001110010011181101111100000191000011000000
TABLE 5Modulation symbol d(10) for PUCCH formats 2a and 2b [3].PUCCH formatb(20), . . . , b(Mbit − 1)d(10)2a0 11−12b00 101−j10 j11−1
Shown in FIG. 1 is the transmission scheme used for PUCCH formats 2/2a/2b of Rel. 8/9 LTE standard. In this scheme, the first 10 QPSK modulation symbols d0, d1, . . . , d9 of the PUCCH payload are each spread by a cyclic shift sequence ru,v(α)(i) of length 12, for i=0, 1, . . . , 11. Thus, each modulation symbol is spread into 12 complex values, which are then mapped onto 12 subcarriers within one physical resource block (PRB) 110 of one single-carrier FDMA (SC-FDMA) symbol. For normal cyclic prefix subframe type, there are 7 SC-FDMA symbols in each slot, two of which are used for demodulation reference signal (RS). Therefore, there are 10 SC-FDMA symbols available in each subframe (consisting of 2 consecutive slots) for transmitting the 10 modulation symbols of PUCCH payload. Note that the 11th modulation symbol d10 is conveyed by modulating the RS.
The cyclic shift sequence ru,v(α)(i) is a constant amplitude zero autocorrelation (CAZAC) sequence, which has a constant amplitude and has the property that it is orthogonal to its cyclically shifted version. Therefore, by using different cyclic shift versions of the same sequence, different UEs can be multiplexed in the same time/frequency source. Another property of a CAZAC sequence is that its discrete Fourier transform (DFT) is another CAZAC sequence. Therefore, the complex sequence, dlru,v(α)(i), i=0, 1 . . . , 11, that is mapped onto the 12 subcarriers of a PRB can be thought of as the DFT of a time-domain constant amplitude sequence. Consequently, the time waveform obtained after the inverse fast Fourier transform (IFFT) operation is a time-interpolated version of this time-domain CAZAC sequence and, therefore, has a lower peak-to-average power ratio than an Orthogonal Frequency Division Multiplexing (OFDM) time waveform, which is obtained by performing the IFFT on a sequence of quadrature amplitude modulation (QAM) modulation symbols.
From the above description, it can be seen that the transmission scheme in FIG. 1 can support up to only 10 modulation symbols. This in turn limits PUCCH payload size. Therefore, there is a need for a method and apparatus for multiple access and transmit diversity schemes in an SC-FDMA system.