Bit-Interleaving and Modulation Mapping
[Coded Modulation and H-ARQ]

For coded-modulation formats 0-5, let $D=(N_\mathrm{d}-N_\mathrm{z})/IntDepth$ where $IntDepth$ depends on the particular transport channel at hand. Each output bit from the convolutional coder, $c_i$, shall be placed in the set $C_{i\mathrm{mod}D}$. The bits in each set are permuted based on a pseudo-random sequence and then combined to form 2,4 or 6-tuples depending on the modulation order of the coded-modulation format. The interleaving permutation sequence depends on $D$ and the number of coded bits.

For the SACH, $D$ is the number of allocated frequency groups. The above interleaving strategy shall be applied with this value.

The QAM modulated symbols are mapped according to the Gray mapping as shown in the following figures. QAM symbols must be scaled to ensure constant average energy independent of the modulation order. The scaling factors are $1/\sqrt(2),1/\sqrt{10}$ and $1/\sqrt{42}$ for QPSK, 16-QAM and 64-QAM respectively.

QAMmodulation.png

QAM Modulation Mapping

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