Page 777 - 5G Basics - Core Network Aspects

Transport aspects 2

The constellation points are denoted (X, Y). The valid values of X and Y are odd integers ±1, ±3, ±5, etc. For
convenience of illustration, each constellation point in Figure 10-10 through Figure 10-14 is labelled by an
integer whose unsigned binary representation is (vb−1 vb−2 ... v1 v0).
10.2.1.4.2.1 Even values of b

For even values of b, the values X and Y of the constellation point (X, Y) shall be determined from extracted
set of the b bits (vb–1, vb–2,...,v1,v0) as follows. The values X and Y shall be odd integers with two's
complement binary representations (vb–1 vb–3 ... v1 1) and (vb–2 vb–4 ... v0 1), respectively. The MSBs, vb–1 and
vb–2, shall be the sign bits for X and Y, respectively. Figure 10-10 shows example constellations for b = 2 and
b = 4.

Figure 10-10 – Constellation labels for b = 2 and b = 4

NOTE – The 4-bit constellation may be obtained from the 2-bit constellation by replacing each label n by the 2 × 2
block of labels:
4n+1 4n+3
4n 4n+2
The same procedure may be used to construct the larger even-bit constellations recursively. All the constellations
defined for even values of b are square in shape.
10.2.1.4.2.2 Odd values of b

Figure 10-11 shows the constellation for the case b = 1.

Figure 10-11 – Constellation labels for b = 1
The NCONEBIT/2 2-bit words generated by the trellis encoder shall be mapped on two 1-bit subcarriers
using the same labelling for 1-bit constellations as described above. An example for mapping of a 2-bit
word (v1 v0) for v0 = 1 and v1 = 0 is shown in Figure 10-12.

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