ff-Chu sequences from the same set of Zadoff-Chu sequences or different shifts of the same sequence. The demodulation and sounding reference signals are shown in Figure 9-73. 9.15.7 Physical Control Channels The Physical Downlink Control Channel (PDCCH) is primarily used to carry scheduling information to individual UEs, i.e., resource assignments for uplink and downlink data and control information. The PDCCH is located in the first few OFDM symbols of a subframe. For frame structure Type 2, PDCCH can also be mapped to the first two OFDM symbols of the DwPTS field. An additional Physical Control Format Indicator Channel (PCFICH), located on specific resource elements in the first OFDM symbol of the subframe, is used to indicate the number of OFDM symbols occupied by the PDCCH (1, 2, 3, or 4 OFDM symbols may be consumed where 4-OFDM-symbol PDCCH is only used when operating in the minimum supported system bandwidth). Depending on the number of users in a cell and the signaling formats conveyed on PDCCH, the size of PDCCH may vary. The information carried in PDCCH is referred to as Downlink Control Information (DCI), where depending on the purpose of the control message, different DCI formats are defined [108]. Note that DCI formats in 3GPP LTE are analogous to IEEE 802. 16m A-MAP information elements. As an example, the information content of DCI format 1 is shown in Table 9-22. DCI format 1 is used for the assignment of downlink shared channel resources when no spatial multiplexing is used (i.e., the scheduling information is only provided for one codeword). This viiiA Zadoff-Chu sequence is a complex-valued sequence with constant amplitude property whose cyclically-shifted versions exhibit low cross-correlation. Thus, under certain conditions, the cyclically-shifted versions of each sequence remains orthogonal to one another. A Zadoff-Chu sequence that has not been shifted is referred to as a Root Sequence. The uth root Zadoff-Chu sequence of prime length N is defined as follows [125]: (N is an odd integer) (N i