format version of PUCCH format 0, which can carry up to 2 bits, using 4-14 OFDM symbols over one resource block per symbol in frequency. The OFDM symbols are split between symbols used for control information and symbols desig- nated to the reference signals to enable coherent reception. The number of symbols used for control information and reference signals is a trade-off between channel estimation accuracy and energy in the information part. It was shown that a reasonable trade-off would be achieved if half of the symbols are used for reference signals. The block of bits b(0), b(NUCI 1)|Nuci =0,1 = is modulated using BPSK for a single-bit payload and 610 Chapter 4 QPSK for double-bit payload, resulting in a complex-valued symbol d(0). The complex- valued symbol d(0) is multiplied by a sequence such that y(n) = The block of complex-valued symbols y(0), y(11) is block-wise spread with the (DFT) orthogonal sequence wi(m) = exp(j2(m)/N5F) such that n=0,1,. , 11;m=0,1,.. NPUCCH-F SF,m' -1 where m' = 0 when there is no intra-slot frequency hopping and m'=0,1 when intra-slot hopping is enabled. The parameter NSUMCH-FI PUCCH-F1 SF,m and the orthogonal sequence wi(m) are defined in [6]. In case of a PUCCH transmission spanning multiple slots, the complex- valued symbol d(0) is repeated for the subsequent slots. The sequence z(n) is scaled with the scaling factor BPUCCH-F1 in order to adjust the transmit power and is mapped sequen- tially to resource elements (k,1) if they are not used by DM-RS. The mapping to resource elements (k,1) designated to PUCCH transmission is in increasing order of frequency and then time over the assigned physical resource block on a single-antenna port. The time- frequency structure of PUCCH format 1 is illustrated in Fig. 4.79. One or two UCI bits BPSK/QPSK modulation Cyclic shift Per symbol pseudo random variation Phase rotation Configurable ID Base sequence Per slot pseudo random variation Base sequence Length 4 orthogonal sequence DM-RS Length 5 orthogonal sequence Active uplink No frequ