PEF22827EL-V11 Lantiq, PEF22827EL-V11 Datasheet - Page 63

• Manufacturer Part Number: PEF22827EL-V11
• Manufacturer: Lantiq

Specifications of PEF22827EL-V11

• Lead Free Status / RoHS Status: Supplier Unconfirmed

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4.4.1.1
Before Reed Solomon (RS) encoding, a self-synchronizing algorithm scrambles
(randomizes) the frame header (without the SYNC word), the payload on the fast
channel and the payload on the slow channel, where
the slow channel. It scrambles each stream separately, using the algorithm in
Equation
4.4.1.2
Reed Solomon encoding adds FEC redundancy bytes to
a code word with
difference between the number of bytes in the code word and the number of data bytes
(
The number of corrected bytes per Reed Solomon code word is half the number of FEC
bytes or: (
In the slow stream, the Reed Solomon code word (
K
payload bytes in the slow stream and 16 is the number of FEC bytes.
In the fast stream, the Reed Solomon code word (
PF
the Reed Solomon code word for the fast stream.
The slow channel and the fast channel are encoded separately. The fast channel
encoder can be programmed.
4.4.1.3
Interleaving on the slow stream improves Reed Solomon error correction when there is
pulse noise. Reed Solomon codes in the transmission frame of the slow stream are
interleaved before transmission by a convolutional interleaver.
The interleaver parameters summarized in
•
•
•
Preliminary Data Sheet
N K
D
=
out
Interleaving
Construction of a Transmission Frame
Splitting the Transmission Frame into PMD Frames
N
I
block is
D
correction).
n
is the number of payload bytes in the fast stream and
OC
= The interleaver block length in bytes. The number of bytes in each interleaver
= D
= Slow Payload (PS) + 19 bytes.
= The interleaving depth, in bytes, controls the level of noise protection (erasure
).
+
in
N K
n
PS
(1), regardless of the configuration (LT or NT).
Scrambling
Reed Solomon Encoding
Interleaving
N
, where
/8 or
D
D
) 2, with truncation to the lower integer.
out
n - 18
N
N
/4. Bytes within the interleaver blocks are numbered from 0 to
1 is the number of bytes that separate any two sequential bytes of
OC
bytes (
is 3 for the 3-byte operations channel field,
D
out
n - 23
N
>
K
)
.
The number of FEC (redundancy) bytes is the
63
Table 23
Functional Description – Digital Block
N
,
K
) is
are:
N
OC
,
N
K
K
) is
=
RF
is included in the payload of
original data bytes to create
PF
N
is the number of bytes in
+
=
RF
OC
PS
Rev. 1.1, 2005-01-30
and
is the number of
+
K
PS
VDSL6100i
PEF 22827
=
PF
+ 16 and
, where
I
(1)
1.