MINI-LINKEandEMicro
Multiplexer
The three different data types together with check bits and frame lock bits are
sent in a composite data format defined by the frame format that is loaded into
a Frame Format RA M. The 12 frame alignment signal bits are placed at the
beginning of the frame. Stuffing bits are inser t ed into the composite frame.
Scrambling and FEC Encoding
The synchronous scrambler has a length of 2
17
– 1 and is synchronized each
eighth frame (super frame). The FEC bits are inserted according to the frame
format and are calculated using an interleaving scheme.
The composite data stream consists of a 125 µs long frame, which contains the
above described data types.
Radio Channel Frame Structure
The figure below shows the radio channel frame structure for 2x2 Mbit/s.
T1
+
CHK
T2
+
T1
T2
+
S2
T1
+
T2
T1
+
FEC
T2
+
T1
C1
+
T2
T1
+
T2
T1
+
S1
T2
+
T1
SC1
+
T2
T1
+
T2
T1
+
SC1
T2
+
T1
S2
+
T2
T1
+
T2
FEC
+
C2
2 2222 2 162224 2 2 2 12220 2
format
FAS T1
+
T2
T1
+
K1
T2
+
T1
S1
+
T2
T1
+
T2
T1
+
K2
T2
+
T1
T2
+
S2
T1
+
T2
T1
+
K1
T2
+
T1
FEC
+
T2
Number
of bits
12 102102 8 2102102102
Frame
5508
Frame length 125
s
T1 = Data from traffic channel 1 T2 = Data from traffic channel 2
K1 = Stuffing control T1 K2 = Stuffing control T2
S1 = Not used S2 = Not used
SC1 = Not used
C1 = HCC1 C2 = HCC2
CHK = Check bits FAS = Frame Alignment Signal
FEC = Forward Error Correction
Figure 39 Example of radio channel frame structure, 2x2 Mbit/s
48
AE/LZT 110 2012 R8C 2002-03-04
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