User Manual

ArchitectureNortel Networks Confidential 3–5
S8000/S8002/S8006 BTS Reference Manual
Each message is transmitted in synchronization with the 4Fbit clock and includes
the following:
the system time in six bytes (flag included)
the address of the DRX (or e–DRX) that transmits the information in one byte
the code of the send frequency on 10 bits
the send power commands in one byte
the NRZ message of the send data in 19 bytes
Up to 16 transmitters can be connected to this bus.
For multi–cell sites, all the cells can be connected onto a single FH bus or there may
be one FH bus per cell, depending on the capacity of the site.
3.1.3.2 Private PCM
Up to six private PCMs transport data between the DRXs (or e–DRXs) and the BCF
unit or CBCF Module. Each Private PCM supports up to four DRXs (or e–DRXs).
Each Private PCM has a 64 kbit/s time slot (TS) distributed to all DRXs (or
e–DRXs) and carries the GSM TIME signal (TS31).
Each private PCM allocates the following time slots (TS) for each DRX (or
e–DRX):
three TSs (64 kbit/s logical channels) of transparent data (traffic/signaling)
one TS (64 kbit/s logical channel) processed by the gateway for the O&M
channel, an adaptation of the O&M bus of the CSWM card
A group of six TSs, three of which are used, is allocated to each DRX (or e–DRX),
as follows:
Traffic Traffic O&M TX
OML/RSL
ÁÁ
ÁÁ
1 2 3 4 5 6
Á
Á
TS 0 of the Private PCM is reserved for tests and supports no transmission channel.
A 4.096 MHz clock, slaved to the 4Fbit clock of the synchronization board, is used
for bit synchronization of the Private PCM.
The O&M channel
The O&M channel, not availabale with the COAM version of the BTS, is carried
by a TS of the private PCM and supports O&M data of the TXs. It is a duplex
two–way channel. Each TX has its own O&M channel, present on the only private
PCM that links the TX to the gateway.