Reference Manual

Transmission Interface Handling DS1 1544 kbit/s
Downstream The path for information from the BSC to
the MS, see Figure 105 on page 363.
Upstream The path for information from the MS to
the BSC, see Figure 105 on page 363.
Linear Cascade Chain A cascade of RBS:s according to Figure
105 on page 363.
01_0306A
RBS 2
PCM-A
PCM-B
PCM-A
PCM-B
Downstream Downstream
Mobile
Station
Downstream
Upstream
Upstream
RBS 1
BSC
Upstream
Upstream
Figure 105 Upstream and Downstream
48.3 Functions
48.3.1 Layer 1 Termination DS1 1544 kbit/s
The function is initiated during restart of DXU.
Layer 1 termination on the transport network interface includes:
• Physical and electrical characteristics according to ANSI T1.403
(interface at 1544 kbit/s, one pair for each direction of
transmission, test load impedance 100 ohm, resistive).
•
Frame structure according to ANSI T1.403, ESF. T option only,
see Table 149 on page 362. 8 traffic bits in all frames in the ESF.
• Line coding B8ZS according to AT&T section 4.2.2. (ref. 4).
B8ZS is the only technology to provide 64 kb/s Clear Channel
Capability (64 CCC).
• When no message is sent on the Data Link (DL, message bit m)
in the ESF, an idle pattern (01111110) (ref. ANSI 6.4(2)) is
transmitted. The Data Link is used for RAI (Remote Alarm
Indication, "Yellow Alarm") information in both directions. See
Table 149 on page 362.
• Frame alignment and CRC-6 procedures according to ANSI
T1.403, 24-frame ESF.
EN/LZT 720 0008 R1A
2001-06-26
363 (421)
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