
PEB 3445 E
Functional Description
Data Sheet
45
2001-06-29
4.5
M23 multiplexer and DS3 framer
The DS3 path of the TE3-MUX can be operated in three modes:
M23 multiplex format
C-bit parity format with modified M23 multiplex operation
Full payload rate format
4.5.1
The framing structure of the M23 multiplex signal is shown in
Table 3
. Each DS3
multiframe consists of 7 subframes and each subframe of eight blocks. One block
consists of 85 bits, where the first bit is the overhead (OH) bit and the remaining 84 bits
contain the information bits. The 84 information bits are formed by bit-by-bit interleaving
of the seven DS2 signals or a total of 12 bits from each DS2 signal. The first bit is
assigned to the 1
st
tributary DS2 signal, the second bit is assigned to the 2
nd
tributary
DS2 signal and so on.
M23 multiplex format
Table 3
M23 multiplex format
F
0
, F
1
F
0
and F
1
form the frame alignment pattern. Each DS3 frame consists of 28 F-bits, four per
subframe in block 2, 4, 6 and 8. F
0
and F
1
form the pattern ’1001’. This pattern is repeated in
every subframe.
M
0
, M
1
M
0
and M
1
form the multiframe alignment signal. The M-bit is contained in the OH-bit of the first
block in subframe 5,6 and 7. The multiframe alignment signal is ’010’.
C
11
..C
73
The C-bits control the bit stuffing procedure of the multiplexed DS2 signals.
P
The P-bits contain parity information and are calculated as even parity on all information bits of
the previous DS3 frame. Both P-bits are identical.
Sub-
frame
Block 1 through 8 of a subframe
3
4
1
2
5
6
7
8
DS3-
Multi-
frame
1
2
3
4
5
6
7
X [84] F
1
[84] C
11
[84] F
0
[84] C
12
[84] F
0
[84] C
13
[84] F
1
[84]
X [84] F
1
[84] C
21
[84] F
0
[84] C
22
[84] F
0
[84] C
23
[84] F
1
[84]
P [84] F
1
[84] C
31
[84] F
0
[84] C
32
[84] F
0
[84] C
33
[84] F
1
[84]
P [84] F
1
[84] C
41
[84] F
0
[84] C
42
[84] F
0
[84] C
43
[84] F
1
[84]
M
0
[84] F
1
[84] C
51
[84] F
0
[84] C
52
[84] F
0
[84] C
53
[84] F
1
[84]
M
1
[84] F
1
[84] C
61
[84] F
0
[84] C
62
[84] F
0
[84] C
63
[84] F
1
[84]
M
0
[84] F
1
[84] C
71
[84] F
0
[84] C
72
[84] F
0
[84] C
73
[84] F
1
[84]