se of de-allocation of persistent allocations in the DL/UL, the base station transmits a HARQ Feedback Allocation in the DL/UL Persistent Allocation A-MAP IE. HARQ Identifier Sequence In order to specify the start of a new transmission, one- Number (AI_SN) bit HARQ identifier sequence number is toggled on every new HARQ transmission with the same ACID. If the AI_SN changes, the receiver assumes that the corresponding HARQ transmission belongings to a new encoder packet and discards the previous HARQ transmission with the same ACID. HARQ Channel Identifier (ACID) HARQ channel identifier. HARQ Sub-packet Identifier (SPID) HARQ sub-packet identifier for HARQ-IR (0, 1, 2, or 3). Constellation Rearrangement Version (CRV) CHAPTER 10 The IEEE 802.16m Physical Layer (Part II) Assignable Resource Size (Contiguous LRUs) Increments of 8 LRUs Increments of 4 LRUs Increments of 2 LRUs Increments of 1 LRU LRU Index FIGURE 10-7 An illustration of resource assignment concept (11-bit resource indexing for 20MHz bandwidth) the assignable resource sizes. The ith element of Ia (1<i<96) for an 11-bit resource indexing using 20 MHz bandwidth is defined as follows: i = 1 Ia(i-1)+[96-(i-1)+1 2<i<12 Ia(i-2)+[96-(i-2)+1 i = 2k,7 k k 12 Ia(i -4)+[96-(i-4)+1 i = : 4k,7 k k 12 Ia(i) = (10-7) Ia(i-8)+[96-(i-8)+1 i = 8k,7 k k 11 2048 - 96-k+ 1 92<i<9 Otherwise 10.2 Downlink control channels The resource index RI for an allocation of size S LRUs beginning at LRU l is calculated as follows: Ia(i) > 0 (10-8) not-assignable if la(i) = 0 where 96. The BS first determines if the required resource size is assignable by checking whether the ith element in Ia has a non-zero value. If the size S is assignable, then the 11-bit resource index is determined by adding l to the value of the ith element in Ia. If the required resource is not assignable, the next higher or lower non-zero element in Ia is selected based on the link adaptation scheme. Note that the same scheme can be applied to the 5 and 10 MHz system bandwidths where the length of Ia is 24 and 