he number of LRUs per subframe. The modulation order M (i.e., 2 for QPSK, 4 for 16 QAM, and 6 for 64 QAM) depends on the parameter Isize-offset as shown in Table 9-8. The allocation size and the value of size-offset are set by the serving BS scheduler, which takes into account the resulting modulation order and effective code rate and is subject to the link adaptation. If a burst is partitioned into more than one FEC block, each partitioned FEC block has the same size. The size of the FEC encoder input is denoted by NFB. The set of supported FEC encoder input sizes, including FEC block CRC when applicable, is the subset of the burst size, i.e., NDB of index from 1 to 39. 9.12 Channel coding and modulation Table 9-6 Supported Burst Sizes in IEEE 802.16m [2] Index NDB (Byte) Index NDB (Byte) Index NDB (Byte) 10800 12000 14400 Table 9-7 Minimum-Size Index as a Function of the Allocation Size [2] Allocation Size minimum-size Allocation Size minimum-size Allocation Size minimum-size 16-18 58-64 19-20 65-72 21-22 73-82 23-25 83-90 26-28 91-102 29-32 103-116 33-35 117-131 10-11 36-40 132-145 41-45 146-164 46-50 165-184 14-15 51-57 408 CHAPTER 9 The IEEE 802. 16m Physical Layer (Part I) Table 9-8 Modulation Order Determination Isize-offset M (Allocation Size 2) M (Allocation Size = = 2) M (Allocation Size 1) 10-15 16-18 19-21 22-23 24-31 The burst size NDB including burst CRC and FEC block CRC is defined as NDB KFBNFB. The payload size excluding burst CRC and FEC block CRC is given by NPL = NDB - NDB-CRC IMFB KFB NFB-CRC where IMFB=0(KFB=1) or 1 (KFB 1), NFB-CRC 16, which is the size of FEC block CRC, NDB-CRC = 16, which is the size of burst CRC. The data octets then sequentially enter into the randomization block. The data bits are XOR with the output of a pseudo-random binary sequence generator. The randomization function is initialized with the initial vector for each FEC block. The burst partition module generates KFB FEC blocks and each FEC block is processed by the FEC block CRC encoding function. If KFB 1, the FEC