mance depends only on modulation order and coding rate. The main problem with MCS signaling, as utilized in the IEEE 802.16-2009 standard, [1] is that the set of possible burst sizes depend on allocation size. As an example, in the IEEE 802.16-2009 standard, the burst size of 45 bytes is only possible, if 5 slots are allocated. Therefore, it would be difficult or even impossible to avoid padding. For large burst sizes, padding is avoided by fragmentation or concatenation of the MAC PDUs. For small burst sizes, or delay-sensitive applications such as VoIP or interactive gaming, the PDU size is set by the higher layers and padding is inevitable. Furthermore, in adaptive HARQ operation, it might be impossible to signal the same burst size for different allocation sizes, assuming 9.12 Channel coding and modulation (12,6) QPSK (24,12) QPSK (36,18) QPSK (48,24) QPSK (60,30) QPSK (72,36) QPSK (96,48) QPSK (108,54) QPSK (120,60) QPSK (12,9) QPSK (24,18) QPSK (36,27) QPSK (48,36) QPSK (60,45) QPSK (72,54) QPSK (24,12) QAM (48,24) QAM (72,36) QAM (96,48) QAM (120,60) QAM (24,18) QAM (48,36) QAM (72,54) QAM (36,18) QAM (72,36) QAM (108,54) QAM (36,24) QAM (72,48) QAM (36,27) QAM (72,54) QAM (36,30) QAM (72,60) QAM Eb/No(dB) FIGURE 9-44 The performance of an IEEE 802.16 CTC coder in AWGN channel with various code rates and modulation schemes supported in the standard [124] burst size is signaled in the re-transmission. A finite number of burst sizes independent of allocation size would allow a more efficient design of the channel coding functions. As an example, considering that each DL-PUSC slot, in the IEEE 802. .16-2009 standard, comprises 24 data sub-carriers, and assuming a burst size of 24 bytes and that the SNR supports the use of QPSK 1/2 and 3/4, then the data burst must be transmitted in four slots. If there are five slots available, then the data burst can be sent using QPSK 1/2 with 6 bytes of padding. If there are only three slots available, the data burst must be sent using QPSK 3/4 with 3 bytes of padding. Thu