Transmission Interface Handling DS1 1544 kbit/s
•
Frame structure according to ANSI T1.403, ESF. T option only,
no bit robbing (i.e. 8 traffic bits in each time slot in all frames in
the ESF).
•
Line coding B8ZS according to ANSI T1.107. B8ZS is the only
technology to provide 64 kbit/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 T1.403, section
6.4 (1989)) is transmitted.
•
Frame alignment and CRC-6 procedures according to ANSI
T1.403, 24–frame ESF.
•
Synchronization of layer 1 handling is described in section DS1
Synchronization.
•
Synchronization of the outgoing signals (on the transport network
interface) is according to AT&T Accunet T1.5 Service (TR
62411) Dec. 1990, chapter 6 “Synchronization and Timing” and
derived from the corresponding incoming PCM paths.
•
Fault supervision of each PCM path is performed according to:
−
ANSI T1.403, section 9 (1995)
−
AT&T Accunet T1.5, paragraph 7
This includes detection of the fault conditions LOF, LOS,
ERATE, AIS and RAI. It also includes a consequent action. The
consequent action for the faults LOF, LOS, ERATE, AIS and
UAST downlink is to send RAI patterns (...1111111100000000...)
continuously on the 4 kbit/s link to the remote end. This is
performed for at least one second.
Short Haul
The specific short haul functionality includes the possibility to amplify
the output signal. This is used to adapt the line signal to optimize the
line performance. The receiver dynamic range in short haul mode is +3
to – 6 dB at 772 kHz (0 dB = 6.0 V
p-p
, 100
twisted pair cables).
Long Haul
The specific long haul functionality provides higher sensitivity in the
receiver compared with short haul. In addition the output signal can be
attenuated with an LBO (Line Build Out). The LBO can be used in
manual mode or automatic mode.
The LBO attenuates the signal from the transmitter. It does not produce
simple (resistive) flat loss, but rather simulates cable loss so that the
resulting signal can be handled properly by the receiver equalizer at the
far end. The LBO also reduces near end cross talk.
The receiver dynamic range in long haul mode is 0 to – 30 dB at 772
kHz (0 dB = 6.0 V
p-p
, 100
twisted pair cables).
The default setting of LBO in RBS is:
202 (306)
EN/LZT 123 2697
R5A
1998-08-13
© Ericsson Radio Systems AB
— All Rights Reserved —
