ed sub-band and mini-band CRUs, in units of a sub-band (i.e., N1 PRUs), in FPi is given by the Downlink CRU Allocation Size (DCASj) parameter. For example, the number of sub-band and mini-band CRUs in FP0 is given by DCAS SBO and DCASMBO2 in units of a sub-band and mini-band, respectively. When DFPC = 0, DCAS must be equal to 0. For FP0, the 9.8 Subchannelization and permutation Sub-band Mini-band Frequency CRU/DRU Sub-carrier Partitioning Permutation Partitioning Allocation Permutation CRU(FP0) PRUSB PRUSB DRU( (FP0) CRU(FP1) DRU(FP1) CRU(FP2) PRUMB PPRUMB DRU(FP2) CRU(FP3) DRU(FP3) Multi-cell Procedure FIGURE 9-23 An example of the procedure for formation of downlink CRUs and DRUs for 10 MHz bandwidth [2] value of DCAS SBO is explicitly signaled in the secondary superframe header to indicate the number of sub-bands in unsigned binary format. The Downlink mini-band CRU Allocation Size (DCASMBO) is sent in the secondary superframe header only for partition FP0 whose value depends on the system bandwidth. As an example, the number of sub-band CRUs for FP0 is given by LSB-CRU-FPO = NDCASSBO- The mapping between DCASMBO and the number of mini-band CRUs for FP0 for system bandwidths of 5, 10, and 20 MHz are given in reference [2] and are summarized in Table 9-3. The downlink DRUs are used to form 2-stream distributed LRUs via sub-carrier permutation. The sub-carrier permutation defined for downlink distributed resource allocations within a frequency partition spreads the sub-carriers of the DRU across the entire distributed resource allocation. The Table 9-3 Summary of Downlink Subchannelization and Permutation Parameters [2] Parameters Signaling Field Calculated Bandwidth Signaling from Signaled Procedure (20/10/5 MHz) Mechanism Fields Definition Sector Sub-band and DSAC (5/4/3) S-SFH Number of sub-bands Sub-band Common Mini-band Sub-packet 2 LSB = N1 * KSB Number of PRUs Partitioning Assigned to sub-bands Number of PRUs Assigned to mMini- bands Frequency DFPC (4/3/3) Number of frequency Frequency Partitioning parti