 block is mapped to four subframes within a 40 ms interval and the 40 ms timing is blindly detected, i.e., there is no explicit signaling indicating 40 ms timing, and each subframe is assumed to be self-decodable, i.e., the BCH can be decoded from a single reception, assuming sufficiently good channel conditions. The Physical Uplink Control Channel (PUCCH) carries Uplink Control Information (UCI) including ACK/NACK information related to data packets received in the downlink, CQI reports, precoding matrix index, Rank Indication (RI) for MIMO, and Scheduling Requests (SR). The PUCCH is transmitted on a reserved frequency region in the uplink which is configured by higher layers. Figure 9-78 shows an example for a PUCCH resource allocation. One resource block is reserved at the 9.15 3GPP LTE physical layer protocols One BCH Transport Block 16-bit CRC Insertion Channel Coding and Rate Matching R=1/3 Scambling Modulation (QPSK) Antenna Mapping (SFBC) Demultiplexing Frame 4i Frame 4i+1 Frame 4i+2 Frame 4i+3 4 Radio Frame = 40 ms FIGURE 9-77 Master information block transmission over PBCH edge of the bandwidth and inter-slot hopping is applied. In TDD mode, the PUCCH is not transmitted in special subframes. Note that a UE only uses PUCCH when it does not have any data to transmit on PUSCH. If a UE has data to transmit on PUSCH, it will multiplex the control information with data on PUSCH. Depending on the type of information that PUCCH can carry, different PUCCH formats are specified, see Table 9-25. When a UE sends a HARQ ACK/NACK in response to a downlink PDSCH transmission, it will derive the exact PUCCH resource to use from the PDCCH transmission (i.e., the number of the first control channel element used for the transmission of the corresponding downlink resource assignment). When a UE has a scheduling request or CQI to send, higher layers will configure the exact PUCCH resource. The PUCCH formats 1, 1a, and 1b are based on cyclic shifts from a Zadoff-Chu type of sequence [102,107]; i.e., the modulated data symbol