bled with a UE-specific scrambling sequence to generate a block of scrambled bits and then modulation is performed to generate the complex-valued symbols. QPSK, 16-QAM, and 64-QAM are the three modulation schemes that can be used; however 64-QAM is optional for the terminals. The block of complex-valued symbols is divided into smaller sets, each corresponding to one SC-FDMA symbol. Then, transform precoding is applied that results in a block of complex-valued symbols. These complex-valued symbols are mapped to resource elements. Finally, a complex-valued time-domain SC-FDMA signal for each antenna port is generated. Modulation and upconversion to the carrier frequency of the complex-valued SC-FDMA baseband signal for each antenna port is shown in Figure 3.9. The filtering required prior to transmission is defined by the requirements in [15]. Resource Modulation Transform SC-FDMA Scrambling element mapper precoder signal gen. mapper Figure 3.8 Overview of uplink physical channel processing. Reproduced with permission from © 2009 3GPP [13] Next Generation Mobile Communications Ecosystem COS (2rft) Re {s,(t)} si(t) Split Filtering Im {s,(t)} -sin (2rft Figure 3.9 Uplink modulation. Reproduced with permission from C 2009 3GPP [13] 3.5.4.1.2 PUCCH PUCCH carries uplink control information and is never transmitted simultaneously with the PUSCH from the same UE. For frame structure type 2, the PUCCH is not transmitted in the UpPTS field. The physical uplink control channel supports multiple formats as shown in Table 3.3. Formats 2a and 2b are supported for normal cyclic prefix only. The PUCCH is mapped to a control channel resource in the uplink. A control channel resource is defined by a code and two resource blocks, consecutive in time, with hopping at the slot boundary [14]. Depending on presence or absence of uplink timing synchronization, the uplink physical control signaling can differ. In the case of time synchronization being present, the outband control signaling consists of CQI, ACK/NAK and Scheduling Request (