User's Manual

Open Information
DESCRIPTION 8 ( 25 )
ERA/RGN/PD Jennie Bergström 5/1551-HRB 105 102/1 Uen
ERA/RKF/TU Carl Helander 2003-01-28 C
Prepared (also subject responsible if other) No
Approved Checked Date Rev Reference
E
4.2 CU
The CU keeps the RBS in operation if a short voltage drop should occur on
the incoming -48 VDC distribution.
4.3 BB Subrack
Baseband functionality handles dedicated and common channels to UE.
The BB subrack comprises an interface for the connection with an RNC, an
MP cluster, the external ATM interface termination as well as all functionality in
the baseband domain except for average output power limiter, power clipping,
delay- and gain adjustment which all are located in the RF subrack.
The following sections gives a brief description of the boards in the subrack.
4.3.1 ETB
The Exchange Terminal Board (ETB) serves as an interface between the
transmission cables and the Asynchronous Transfer Mode (ATM) switch on an
Switch Core Board (SCB). The ETB provides the connections for the Iub and
remote Mub (management interface) interfaces.
The type of ETBs depends on the transmission standard. For more information
on the transmission standards, please refer to page 11.
4.3.2 SCB
The SCB contains an ATM switch and is, via the backplane, connected to the
ATM switch ports located on other boards. An SCB can also be connected with
up to four other SCBs located in other subracks and to the RF subrack for
ATM switching parts.
The SCB also has a connector and filter for the system power. The system
power is distributed within the subrack via the backplane. The SCB also
supervises and controls the subrack fans.
The SCB can be duplicated to provide redundancy. Of one SCB stops working,
the other takes over the traffic. The first slot and the last slot the BB and RF
subrack are reserved for SCBs.
4.3.3 RAXB
The Random Access/Receiver Board (RAXB) comprises the BB receiver part,
which takes care of:
• of decoding, searching and RAKE receiving for dedicated and random
access transport channels
• cell combination for softer hand over. A softer hand over takes place when
a UE moves from one sector to another using the same frequency.