System information

FCD 901 48
Issue R2A, 07.2009
XMP1 Release 5.5 System Description
Frame structure
Page 2-6 Proprietary Information Aastra
Service digits
The service digits are transmitted in the frames which do not include the
frame alignment signal.
Bit X in position 1 is used for transmitting the CRC4 multiframe alignment
signal. If the CRC4 procedure is not applied, bit X is set to logic 1.
The bit in position 2 is set to logic 1 in order to avoid that the service digits
can pretend to include a frame alignment signal.
Bit D in position 3 is required for signalling an urgent alarm (alarm = 1).
Bit N in position 4 is used to signal a non-urgent alarm (alarm status =1).
The Y-bits (Sa bit) in positions 5 to 8 are used as system channel and control
channel for network configuration and network surveillance.
The Y- bit (Sa bit) in position 5 is required to control the clock priorities in an
XMP1 network.
The Y-bits (Sa bit) in positions 7 and 8 are used to transmit the system
channel.
XMP1 permits the Y-bits (positions 5 to 8) to be re-routed via traffic channel
29. In this case, they can be used to transmit the system channel of
third-party units.
Multiframe
Signalling transmission
The signalling information for the 30 channels available on each port is
digitized on the channel modules and transmitted in time slot 16.
The multiframe includes sixteen 8-bit signals which are transmitted in time
slots 16 of the multiframe. The duration of the multiframe is 2 ms, i.e. it is 16
times longer than a single multiplex frame. The 16 frames included in a
multiframe are numbered from 0 to 15.
Frame 0
In frame 0 of the multiframe, the multiframe alignment signal (4 bits) is
transmitted in bit positions 1 to 4, whereas the multiframe service digits (4
bits) are transmitted in positions 5 to 8.
Table 2.B: Service digits
Bit position 12345678
Binary value X 1 D N Y Y Y Y
Table 2.C: Frame 0
Bit position 1 2 3 4 5 6 7 8
Binary value 0 0 0 0 Y Dk Y Y