Page 765 - 5G Basics - Core Network Aspects

Transport aspects 2

10.1.2.1 Vectoring interfaces

Vectoring interfaces ε(k,n) and η(k,n) presented in Figure 10-1 (for downstream direction) and clarified in
detail in Figure 10-16 are between the precoder and VCE and post-canceller and VCE, respectively. The
primitives at vectoring interfaces provide the VCE with the signals necessary to perform channel estimation.
The VCE, via vectoring interfaces, provides channel matrix coefficients to the precoder (via ε(k,n) interface,
see Figure 10-16) and to the post-canceller (via η(k,n) interface), and TIGA settings to the FTU-O for
communication to the FTU-R. Both vectoring interfaces are vendor discretionary.

10.2 Symbol encoder
This clause describes the data symbol, initialization symbol and pilot symbol encoders of the PMD (see
Figure 10-1).
10.2.1 Data symbol encoder
The data symbol encoder provides the following functions:
– Bytes to bits padding;
– Tone ordering;
– Trellis coding;
– Constellation mapping;
– Constellation point scaling.

The tone ordering and trellis coding shall be performed differently for data symbols and RMC symbols, as
defined in clauses 10.2.1.2 and 10.2.1.3, respectively. The functional model of the data symbol encoder is
defined in Figure 10-2.

Figure 10-2 – Functional model of the data symbol encoder
10.2.1.1 Bytes to bits padding

The data frames crossing the  interface from the PMS-TC include an integer number of bytes. Bits shall be
extracted LSB first from the bytes received. Bit padding shall be used if the number of bits loaded onto one
symbol is not an integer multiple of eight.

For data symbols, up to seven padding bits shall be appended to the end of the data frame prior to the
symbol encoding. The number of padding bits shall be equal to the difference between the number of data
bits modulated over the symbol (LD) and the size of the data frame in bits (8 × BD), where BD=floor(LD/8).
Figure 10-3 (on the top) shows the data symbol structure.
For RMC symbols, padding bits shall be appended separately to the RMC part and the user data part of the
data frame. The number of padding bits added after the RMC data shall be equal to the difference between
the number of data bits modulated on RMC tones (LRMC) and the size of the RMC frame in bits (8 × NRMC),

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